diff --git a/docs/iris/src/userguide/interpolation_and_regridding.rst b/docs/iris/src/userguide/interpolation_and_regridding.rst
index 0ce7b5c774..eb8ecc4aca 100644
--- a/docs/iris/src/userguide/interpolation_and_regridding.rst
+++ b/docs/iris/src/userguide/interpolation_and_regridding.rst
@@ -47,7 +47,7 @@ The specified coordinate must exist on the cube being interpolated! For example:
 are all examples of valid sample points.
 
 The values for coordinates that correspond to date/times can be supplied as
-datetime.datetime or netcdftime.datetime instances,
+datetime.datetime or cftime.datetime instances,
 e.g. ``[('time', datetime.datetime(2009, 11, 19, 10, 30))]``).
 
 Let's take the air temperature cube we've seen previously:
diff --git a/docs/iris/src/whatsnew/contributions_2.1/newfeature_2018-May-23_cftime.txt b/docs/iris/src/whatsnew/contributions_2.1/newfeature_2018-May-23_cftime.txt
new file mode 100644
index 0000000000..de74eeb8d6
--- /dev/null
+++ b/docs/iris/src/whatsnew/contributions_2.1/newfeature_2018-May-23_cftime.txt
@@ -0,0 +1,2 @@
+Iris updated its time-handling functionality from the netcdf4-python builtin netcdftime to the standalone module cftime.
+cftime is entirely compatible with netcdftime.
\ No newline at end of file
diff --git a/lib/iris/analysis/__init__.py b/lib/iris/analysis/__init__.py
index b48fab6baa..8cf1a5d2a7 100644
--- a/lib/iris/analysis/__init__.py
+++ b/lib/iris/analysis/__init__.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2017, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -2181,7 +2181,7 @@ def interpolator(self, cube, coords):
 
             The values for coordinates that correspond to date/times
             may optionally be supplied as datetime.datetime or
-            netcdftime.datetime instances.
+            cftime.datetime instances.
 
             For example, for the callable returned by:
             `Linear().interpolator(cube, ['latitude', 'longitude'])`,
@@ -2364,7 +2364,7 @@ def interpolator(self, cube, coords):
 
             The values for coordinates that correspond to date/times
             may optionally be supplied as datetime.datetime or
-            netcdftime.datetime instances.
+            cftime.datetime instances.
 
             For example, for the callable returned by:
             `Nearest().interpolator(cube, ['latitude', 'longitude'])`,
diff --git a/lib/iris/coord_categorisation.py b/lib/iris/coord_categorisation.py
index 0c6aadd3f7..3c3303441d 100644
--- a/lib/iris/coord_categorisation.py
+++ b/lib/iris/coord_categorisation.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2016, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -173,7 +173,7 @@ def add_day_of_year(cube, coord, name='day_of_year'):
     (1..366 in leap years).
 
     """
-    # Note: netcdftime.datetime objects return a normal tuple from timetuple(),
+    # Note: cftime.datetime objects return a normal tuple from timetuple(),
     # unlike datetime.datetime objects that return a namedtuple.
     # Index the time tuple (element 7 is day of year) instead of using named
     # element tm_yday.
diff --git a/lib/iris/coords.py b/lib/iris/coords.py
index 3b2b2f5eb1..e4a8eb35f2 100644
--- a/lib/iris/coords.py
+++ b/lib/iris/coords.py
@@ -32,7 +32,7 @@
 import warnings
 import zlib
 
-import netcdftime
+import cftime
 import numpy as np
 import numpy.ma as ma
 
@@ -267,13 +267,13 @@ def __common_cmp__(self, other, operator_method):
                                    operator.ge, operator.le):
             raise ValueError("Unexpected operator_method")
 
-        # Prevent silent errors resulting from missing netcdftime
+        # Prevent silent errors resulting from missing cftime
         # behaviour.
-        if (isinstance(other, netcdftime.datetime) or
-                (isinstance(self.point, netcdftime.datetime) and
+        if (isinstance(other, cftime.datetime) or
+                (isinstance(self.point, cftime.datetime) and
                  not isinstance(other, iris.time.PartialDateTime))):
             raise TypeError('Cannot determine the order of '
-                            'netcdftime.datetime objects')
+                            'cftime.datetime objects')
 
         if isinstance(other, Cell):
             # Cell vs Cell comparison for providing a strict sort order
@@ -336,7 +336,7 @@ def __common_cmp__(self, other, operator_method):
                 else:
                     me = max(self.bound)
 
-            # Work around to handle netcdftime.datetime comparison, which
+            # Work around to handle cftime.datetime comparison, which
             # doesn't return NotImplemented on failure in some versions of the
             # library
             try:
@@ -1127,7 +1127,7 @@ def cell(self, index):
             If `iris.FUTURE.cell_datetime_objects` is True, then this
             method will return Cell objects whose `points` and `bounds`
             attributes contain either datetime.datetime instances or
-            netcdftime.datetime instances (depending on the calendar).
+            cftime.datetime instances (depending on the calendar).
 
         .. deprecated:: 2.0.0
 
diff --git a/lib/iris/cube.py b/lib/iris/cube.py
index 4de1ba93c7..9c42299c42 100644
--- a/lib/iris/cube.py
+++ b/lib/iris/cube.py
@@ -3640,7 +3640,7 @@ def interpolate(self, sample_points, scheme, collapse_scalar=True):
             A sequence of (coordinate, points) pairs over which to
             interpolate. The values for coordinates that correspond to
             dates or times may optionally be supplied as datetime.datetime or
-            netcdftime.datetime instances.
+            cftime.datetime instances.
         * scheme:
             The type of interpolation to use to interpolate from this
             :class:`~iris.cube.Cube` to the given sample points. The
diff --git a/lib/iris/fileformats/nimrod_load_rules.py b/lib/iris/fileformats/nimrod_load_rules.py
index 3fdf2d22c1..3dbb47cc35 100644
--- a/lib/iris/fileformats/nimrod_load_rules.py
+++ b/lib/iris/fileformats/nimrod_load_rules.py
@@ -23,7 +23,7 @@
 import warnings
 
 import cf_units
-import netcdftime
+import cftime
 import numpy as np
 
 import iris
@@ -76,9 +76,9 @@ def units(cube, field):
 
 def time(cube, field):
     """Add a time coord to the cube."""
-    valid_date = netcdftime.datetime(field.vt_year, field.vt_month,
-                                     field.vt_day, field.vt_hour,
-                                     field.vt_minute, field.vt_second)
+    valid_date = cftime.datetime(field.vt_year, field.vt_month,
+                                 field.vt_day, field.vt_hour,
+                                 field.vt_minute, field.vt_second)
     point = TIME_UNIT.date2num(valid_date)
 
     bounds = None
@@ -97,9 +97,9 @@ def time(cube, field):
 def reference_time(cube, field):
     """Add a 'reference time' to the cube, if present in the field."""
     if field.dt_year != field.int_mdi:
-        data_date = netcdftime.datetime(field.dt_year, field.dt_month,
-                                        field.dt_day, field.dt_hour,
-                                        field.dt_minute)
+        data_date = cftime.datetime(field.dt_year, field.dt_month,
+                                    field.dt_day, field.dt_hour,
+                                    field.dt_minute)
 
         ref_time_coord = DimCoord(TIME_UNIT.date2num(data_date),
                                   standard_name='forecast_reference_time',
diff --git a/lib/iris/fileformats/pp.py b/lib/iris/fileformats/pp.py
index 3445255654..24dab953f0 100644
--- a/lib/iris/fileformats/pp.py
+++ b/lib/iris/fileformats/pp.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2017, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -35,7 +35,7 @@
 import cf_units
 import numpy as np
 import numpy.ma as ma
-import netcdftime
+import cftime
 
 from iris._deprecation import warn_deprecated
 from iris._lazy_data import as_concrete_data, as_lazy_data, is_lazy_data
@@ -1425,8 +1425,8 @@ class PPField2(PPField):
 
     def _get_t1(self):
         if not hasattr(self, '_t1'):
-            self._t1 = netcdftime.datetime(self.lbyr, self.lbmon, self.lbdat,
-                                           self.lbhr, self.lbmin)
+            self._t1 = cftime.datetime(self.lbyr, self.lbmon, self.lbdat,
+                                       self.lbhr, self.lbmin)
         return self._t1
 
     def _set_t1(self, dt):
@@ -1440,14 +1440,14 @@ def _set_t1(self, dt):
             delattr(self, '_t1')
 
     t1 = property(_get_t1, _set_t1, None,
-                  "A netcdftime.datetime object consisting of the lbyr, lbmon,"
+                  "A cftime.datetime object consisting of the lbyr, lbmon,"
                   " lbdat, lbhr, and lbmin attributes.")
 
     def _get_t2(self):
         if not hasattr(self, '_t2'):
-            self._t2 = netcdftime.datetime(self.lbyrd, self.lbmond,
-                                           self.lbdatd, self.lbhrd,
-                                           self.lbmind)
+            self._t2 = cftime.datetime(self.lbyrd, self.lbmond,
+                                       self.lbdatd, self.lbhrd,
+                                       self.lbmind)
         return self._t2
 
     def _set_t2(self, dt):
@@ -1461,7 +1461,7 @@ def _set_t2(self, dt):
             delattr(self, '_t2')
 
     t2 = property(_get_t2, _set_t2, None,
-                  "A netcdftime.datetime object consisting of the lbyrd, "
+                  "A cftime.datetime object consisting of the lbyrd, "
                   "lbmond, lbdatd, lbhrd, and lbmind attributes.")
 
 
@@ -1478,8 +1478,8 @@ class PPField3(PPField):
 
     def _get_t1(self):
         if not hasattr(self, '_t1'):
-            self._t1 = netcdftime.datetime(self.lbyr, self.lbmon, self.lbdat,
-                                           self.lbhr, self.lbmin, self.lbsec)
+            self._t1 = cftime.datetime(self.lbyr, self.lbmon, self.lbdat,
+                                       self.lbhr, self.lbmin, self.lbsec)
         return self._t1
 
     def _set_t1(self, dt):
@@ -1493,14 +1493,14 @@ def _set_t1(self, dt):
             delattr(self, '_t1')
 
     t1 = property(_get_t1, _set_t1, None,
-                  "A netcdftime.datetime object consisting of the lbyr, lbmon,"
+                  "A cftime.datetime object consisting of the lbyr, lbmon,"
                   " lbdat, lbhr, lbmin, and lbsec attributes.")
 
     def _get_t2(self):
         if not hasattr(self, '_t2'):
-            self._t2 = netcdftime.datetime(self.lbyrd, self.lbmond,
-                                           self.lbdatd, self.lbhrd,
-                                           self.lbmind, self.lbsecd)
+            self._t2 = cftime.datetime(self.lbyrd, self.lbmond,
+                                       self.lbdatd, self.lbhrd,
+                                       self.lbmind, self.lbsecd)
         return self._t2
 
     def _set_t2(self, dt):
@@ -1514,7 +1514,7 @@ def _set_t2(self, dt):
             delattr(self, '_t2')
 
     t2 = property(_get_t2, _set_t2, None,
-                  "A netcdftime.datetime object consisting of the lbyrd, "
+                  "A cftime.datetime object consisting of the lbyrd, "
                   "lbmond, lbdatd, lbhrd, lbmind, and lbsecd attributes.")
 
 
diff --git a/lib/iris/fileformats/pp_load_rules.py b/lib/iris/fileformats/pp_load_rules.py
index f709ac30c9..88a215546b 100644
--- a/lib/iris/fileformats/pp_load_rules.py
+++ b/lib/iris/fileformats/pp_load_rules.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -295,7 +295,7 @@ def _collapse_degenerate_points_and_bounds(points, bounds=None, rtol=1.0e-7):
     All dimensions are tested, and if degenerate are reduced to length 1.
 
     Value equivalence is controlled by a tolerance, to avoid problems with
-    numbers from netcdftime.date2num, which has limited precision because of
+    numbers from cftime.date2num, which has limited precision because of
     the way it calculates with floats of days.
 
     Args:
diff --git a/lib/iris/fileformats/pp_save_rules.py b/lib/iris/fileformats/pp_save_rules.py
index 7fcc4ab639..84b4980647 100644
--- a/lib/iris/fileformats/pp_save_rules.py
+++ b/lib/iris/fileformats/pp_save_rules.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2017, Met Office
+# (C) British Crown Copyright 2017 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -32,7 +32,7 @@
                                     scalar_coord,
                                     vector_coord)
 from iris.util import is_regular, regular_step
-import netcdftime
+import cftime
 
 
 def _basic_coord_system_rules(cube, pp):
@@ -129,7 +129,7 @@ def _general_time_rules(cube, pp):
         pp.lbtim.ia = 0
         pp.lbtim.ib = 0
         pp.t1 = time_coord.units.num2date(time_coord.points[0])
-        pp.t2 = netcdftime.datetime(0, 0, 0)
+        pp.t2 = cftime.datetime(0, 0, 0)
 
     # Forecast.
     if (time_coord is not None and
@@ -252,10 +252,10 @@ def _general_time_rules(cube, pp):
         pp.t1 = time_coord.units.num2date(time_coord.bounds[0, 0])
         pp.t2 = time_coord.units.num2date(time_coord.bounds[0, 1])
         if pp.t1.month == 12:
-            pp.t1 = netcdftime.datetime(pp.t1.year)
+            pp.t1 = cftime.datetime(pp.t1.year)
         else:
-            pp.t1 = netcdftime.datetime(pp.t1.year-1, 12, 1, 0, 0, 0)
-        pp.t2 = netcdftime.datetime(pp.t2.year, 3, 1, 0, 0, 0)
+            pp.t1 = cftime.datetime(pp.t1.year-1, 12, 1, 0, 0, 0)
+        pp.t2 = cftime.datetime(pp.t2.year, 3, 1, 0, 0, 0)
         _conditional_warning(
             time_coord.bounds[0, 0] != time_coord.units.date2num(pp.t1),
             "modified t1 for climatological seasonal mean")
@@ -278,8 +278,8 @@ def _general_time_rules(cube, pp):
         # TODO: wut?
         pp.t1 = time_coord.units.num2date(time_coord.bounds[0, 0])
         pp.t2 = time_coord.units.num2date(time_coord.bounds[0, 1])
-        pp.t1 = netcdftime.datetime(pp.t1.year, 3, 1, 0, 0, 0)
-        pp.t2 = netcdftime.datetime(pp.t2.year, 6, 1, 0, 0, 0)
+        pp.t1 = cftime.datetime(pp.t1.year, 3, 1, 0, 0, 0)
+        pp.t2 = cftime.datetime(pp.t2.year, 6, 1, 0, 0, 0)
         _conditional_warning(
             time_coord.bounds[0, 0] != time_coord.units.date2num(pp.t1),
             "modified t1 for climatological seasonal mean")
@@ -302,8 +302,8 @@ def _general_time_rules(cube, pp):
         # TODO: wut?
         pp.t1 = time_coord.units.num2date(time_coord.bounds[0, 0])
         pp.t2 = time_coord.units.num2date(time_coord.bounds[0, 1])
-        pp.t1 = netcdftime.datetime(pp.t1.year, 6, 1, 0, 0, 0)
-        pp.t2 = netcdftime.datetime(pp.t2.year, 9, 1, 0, 0, 0)
+        pp.t1 = cftime.datetime(pp.t1.year, 6, 1, 0, 0, 0)
+        pp.t2 = cftime.datetime(pp.t2.year, 9, 1, 0, 0, 0)
         _conditional_warning(
             time_coord.bounds[0, 0] != time_coord.units.date2num(pp.t1),
             "modified t1 for climatological seasonal mean")
@@ -326,8 +326,8 @@ def _general_time_rules(cube, pp):
         # TODO: wut?
         pp.t1 = time_coord.units.num2date(time_coord.bounds[0, 0])
         pp.t2 = time_coord.units.num2date(time_coord.bounds[0, 1])
-        pp.t1 = netcdftime.datetime(pp.t1.year, 9, 1, 0, 0, 0)
-        pp.t2 = netcdftime.datetime(pp.t2.year, 12, 1, 0, 0, 0)
+        pp.t1 = cftime.datetime(pp.t1.year, 9, 1, 0, 0, 0)
+        pp.t2 = cftime.datetime(pp.t2.year, 12, 1, 0, 0, 0)
         _conditional_warning(
             time_coord.bounds[0, 0] != time_coord.units.date2num(pp.t1),
             "modified t1 for climatological seasonal mean")
diff --git a/lib/iris/fileformats/um/_fast_load_structured_fields.py b/lib/iris/fileformats/um/_fast_load_structured_fields.py
index 079a2d457d..5da80d523e 100644
--- a/lib/iris/fileformats/um/_fast_load_structured_fields.py
+++ b/lib/iris/fileformats/um/_fast_load_structured_fields.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2017, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -28,7 +28,7 @@
 
 import itertools
 
-from netCDF4 import netcdftime
+import cftime
 import numpy as np
 
 from iris._lazy_data import as_lazy_data, multidim_lazy_stack
@@ -217,8 +217,8 @@ def _calculate_structure(self):
                 arr_shape = arr.shape[:-1]
                 extra_length = arr.shape[-1]
                 # Flatten out the array apart from the last dimension,
-                # convert to netcdftime objects, then reshape back.
-                arr = np.array([netcdftime.datetime(*args)
+                # convert to cftime objects, then reshape back.
+                arr = np.array([cftime.datetime(*args)
                                 for args in arr.reshape(-1, extra_length)]
                                ).reshape(arr_shape)
                 vector_element_arrays_and_dims[name] = (arr, dims)
diff --git a/lib/iris/pandas.py b/lib/iris/pandas.py
index 780516f3ab..b4e1e9787a 100644
--- a/lib/iris/pandas.py
+++ b/lib/iris/pandas.py
@@ -28,7 +28,7 @@
 
 import cf_units
 from cf_units import Unit
-import netcdftime
+import cftime
 import numpy as np
 import numpy.ma as ma
 import pandas
@@ -59,7 +59,7 @@ def _add_iris_coord(cube, name, points, dim, calendar=None):
 
     # Convert datetime objects to Iris' current datetime representation.
     if points.dtype == object:
-        dt_types = (datetime.datetime, netcdftime.datetime)
+        dt_types = (datetime.datetime, cftime.datetime)
         if all([isinstance(i, dt_types) for i in points]):
             units = Unit("hours since epoch", calendar=calendar)
             points = units.date2num(points)
diff --git a/lib/iris/plot.py b/lib/iris/plot.py
index 7ebe48ae03..64ce54c04c 100644
--- a/lib/iris/plot.py
+++ b/lib/iris/plot.py
@@ -37,8 +37,8 @@
 import matplotlib.pyplot as plt
 from matplotlib.offsetbox import AnchoredText
 import matplotlib.ticker as mpl_ticker
+import cftime
 import matplotlib.transforms as mpl_transforms
-import netcdftime
 import numpy as np
 import numpy.ma as ma
 
@@ -434,7 +434,7 @@ def _fixup_dates(coord, values):
                 raise IrisError(msg)
 
             r = [nc_time_axis.CalendarDateTime(
-                 netcdftime.datetime(*date), coord.units.calendar)
+                 cftime.datetime(*date), coord.units.calendar)
                  for date in dates]
         values = np.empty(len(r), dtype=object)
         values[:] = r
diff --git a/lib/iris/tests/integration/plot/test_netcdftime.py b/lib/iris/tests/integration/plot/test_netcdftime.py
index ea3cdd8d78..b4c19bd3e5 100644
--- a/lib/iris/tests/integration/plot/test_netcdftime.py
+++ b/lib/iris/tests/integration/plot/test_netcdftime.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2016 - 2017, Met Office
+# (C) British Crown Copyright 2016 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -26,7 +26,7 @@
 # importing anything else
 import iris.tests as tests
 
-import netcdftime
+import cftime
 import numpy as np
 
 from iris.coords import AuxCoord
@@ -51,8 +51,8 @@ def test_360_day_calendar(self):
         time_unit = Unit('days since 1970-01-01 00:00', calendar=calendar)
         time_coord = AuxCoord(np.arange(n), 'time', units=time_unit)
         times = [time_unit.num2date(point) for point in time_coord.points]
-        times = [netcdftime.datetime(atime.year, atime.month, atime.day,
-                                     atime.hour, atime.minute, atime.second)
+        times = [cftime.datetime(atime.year, atime.month, atime.day,
+                                 atime.hour, atime.minute, atime.second)
                  for atime in times]
         expected_ydata = np.array([CalendarDateTime(time, calendar)
                                    for time in times])
diff --git a/lib/iris/tests/integration/test_PartialDateTime.py b/lib/iris/tests/integration/test_PartialDateTime.py
index 207d89d150..706cf49f22 100644
--- a/lib/iris/tests/integration/test_PartialDateTime.py
+++ b/lib/iris/tests/integration/test_PartialDateTime.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2017, Met Office
+# (C) British Crown Copyright 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -30,7 +30,7 @@
 class Test(tests.IrisTest):
 
     @tests.skip_data
-    def test_netcdftime_interface(self):
+    def test_cftime_interface(self):
         # The `netcdf4` Python module introduced new calendar classes by v1.2.7
         # This test is primarily of this interface, so the
         # final test assertion is simple.
diff --git a/lib/iris/tests/test_pandas.py b/lib/iris/tests/test_pandas.py
index 12b93addb7..aec432692a 100644
--- a/lib/iris/tests/test_pandas.py
+++ b/lib/iris/tests/test_pandas.py
@@ -27,9 +27,9 @@
 import unittest
 
 import cf_units
+import cftime
 import matplotlib.units
 import netCDF4
-import netcdftime
 import numpy as np
 
 
@@ -101,21 +101,11 @@ def test_time_360(self):
         time_coord = DimCoord([0, 100.1, 200.2, 300.3, 400.4],
                               long_name="time", units=time_unit)
         cube.add_dim_coord(time_coord, 0)
-        # TODO Remove this if statement as we move to cftime
-        if cf_units.__version__ > '1':
-            import cftime
-            expected_index = [cftime.Datetime360Day(2000, 1, 1, 0, 0),
-                              cftime.Datetime360Day(2000, 4, 11, 2, 24),
-                              cftime.Datetime360Day(2000, 7, 21, 4, 48),
-                              cftime.Datetime360Day(2000, 11, 1, 7, 12),
-                              cftime.Datetime360Day(2001, 2, 11, 9, 36)]
-
-        else:
-            expected_index = [netcdftime.Datetime360Day(2000, 1, 1, 0, 0),
-                              netcdftime.Datetime360Day(2000, 4, 11, 2, 24),
-                              netcdftime.Datetime360Day(2000, 7, 21, 4, 48),
-                              netcdftime.Datetime360Day(2000, 11, 1, 7, 12),
-                              netcdftime.Datetime360Day(2001, 2, 11, 9, 36)]
+        expected_index = [cftime.Datetime360Day(2000, 1, 1, 0, 0),
+                          cftime.Datetime360Day(2000, 4, 11, 2, 24),
+                          cftime.Datetime360Day(2000, 7, 21, 4, 48),
+                          cftime.Datetime360Day(2000, 11, 1, 7, 12),
+                          cftime.Datetime360Day(2001, 2, 11, 9, 36)]
 
         series = iris.pandas.as_series(cube)
         self.assertArrayEqual(series, cube.data)
@@ -248,16 +238,9 @@ def test_time_360(self):
         time_coord = DimCoord([100.1, 200.2], long_name="time",
                               units=time_unit)
         cube.add_dim_coord(time_coord, 0)
-        # TODO: Remove this if statement once we move to exclusive cftime.
-        if cf_units.__version__ > '1':
-            # cf_units depends upon cftime, so we can safely assume we
-            # have it.
-            import cftime
-            expected_index = [cftime.Datetime360Day(2000, 4, 11, 2, 24),
-                              cftime.Datetime360Day(2000, 7, 21, 4, 48)]
-        else:
-            expected_index = [netcdftime.Datetime360Day(2000, 4, 11, 2, 24),
-                              netcdftime.Datetime360Day(2000, 7, 21, 4, 48)]
+        expected_index = [cftime.Datetime360Day(2000, 4, 11, 2, 24),
+                          cftime.Datetime360Day(2000, 7, 21, 4, 48)]
+
         expected_columns = [0, 1, 2, 3, 4]
         data_frame = iris.pandas.as_data_frame(cube)
         self.assertArrayEqual(data_frame, cube.data)
@@ -355,14 +338,14 @@ def test_series_datetime_gregorian(self):
             tests.get_result_path(('pandas', 'as_cube',
                                    'series_datetime_gregorian.cml')))
 
-    def test_series_netcdftime_360(self):
+    def test_series_cftime_360(self):
         series = pandas.Series(
             [0, 1, 2, 3, 4],
-            index=[netcdftime.datetime(2001, 1, 1, 1, 1, 1),
-                   netcdftime.datetime(2002, 2, 2, 2, 2, 2),
-                   netcdftime.datetime(2003, 3, 3, 3, 3, 3),
-                   netcdftime.datetime(2004, 4, 4, 4, 4, 4),
-                   netcdftime.datetime(2005, 5, 5, 5, 5, 5)])
+            index=[cftime.datetime(2001, 1, 1, 1, 1, 1),
+                   cftime.datetime(2002, 2, 2, 2, 2, 2),
+                   cftime.datetime(2003, 3, 3, 3, 3, 3),
+                   cftime.datetime(2004, 4, 4, 4, 4, 4),
+                   cftime.datetime(2005, 5, 5, 5, 5, 5)])
         self.assertCML(
             iris.pandas.as_cube(series,
                                 calendars={0: cf_units.CALENDAR_360_DAY}),
@@ -415,12 +398,12 @@ def test_data_frame_masked(self):
             tests.get_result_path(('pandas', 'as_cube',
                                    'data_frame_masked.cml')))
 
-    def test_data_frame_netcdftime_360(self):
+    def test_data_frame_cftime_360(self):
         data_frame = pandas.DataFrame(
             [[0, 1, 2, 3, 4],
              [5, 6, 7, 8, 9]],
-            index=[netcdftime.datetime(2001, 1, 1, 1, 1, 1),
-                   netcdftime.datetime(2002, 2, 2, 2, 2, 2)],
+            index=[cftime.datetime(2001, 1, 1, 1, 1, 1),
+                   cftime.datetime(2002, 2, 2, 2, 2, 2)],
             columns=[10, 11, 12, 13, 14])
         self.assertCML(
             iris.pandas.as_cube(
diff --git a/lib/iris/tests/test_pp_module.py b/lib/iris/tests/test_pp_module.py
index acdaff158e..2c7ac0f1cf 100644
--- a/lib/iris/tests/test_pp_module.py
+++ b/lib/iris/tests/test_pp_module.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -26,7 +26,7 @@
 from types import GeneratorType
 import unittest
 
-import netcdftime
+import cftime
 from numpy.testing import assert_array_equal
 
 import iris.fileformats
@@ -176,7 +176,8 @@ def test_lbproc_access(self):
         self.assertEqual(warn.call_count, 3)
 
     def test_t1_t2_access(self):
-        self.assertEqual(self.r[0].t1.timetuple(), netcdftime.datetime(1994, 12, 1, 0, 0).timetuple())
+        self.assertEqual(self.r[0].t1.timetuple(),
+                         cftime.datetime(1994, 12, 1, 0, 0).timetuple())
 
     def test_save_single(self):
         temp_filename = iris.util.create_temp_filename(".pp")
diff --git a/lib/iris/tests/unit/coords/test_Cell.py b/lib/iris/tests/unit/coords/test_Cell.py
index 9a19962615..452fe12043 100644
--- a/lib/iris/tests/unit/coords/test_Cell.py
+++ b/lib/iris/tests/unit/coords/test_Cell.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -26,7 +26,7 @@
 import datetime
 import numpy as np
 
-import netcdftime
+import cftime
 
 from iris.coords import Cell
 from iris.tests import mock
@@ -44,28 +44,28 @@ def assert_raises_on_comparison(self, cell, other, exception_type, regexp):
         with self.assertRaisesRegexp(exception_type, regexp):
             cell >= other
 
-    def test_netcdftime_cell(self):
+    def test_cftime_cell(self):
         # Check that cell comparison when the cell contains
-        # netcdftime.datetime objects raises an exception otherwise
+        # cftime.datetime objects raises an exception otherwise
         # this will fall back to id comparison producing unreliable
         # results.
-        cell = Cell(netcdftime.datetime(2010, 3, 21))
+        cell = Cell(cftime.datetime(2010, 3, 21))
         dt = mock.Mock(timetuple=mock.Mock())
         self.assert_raises_on_comparison(cell, dt, TypeError,
-                                         'determine the order of netcdftime')
+                                         'determine the order of cftime')
         self.assert_raises_on_comparison(cell, 23, TypeError,
-                                         'determine the order of netcdftime')
+                                         'determine the order of cftime')
         self.assert_raises_on_comparison(cell, 'hello', TypeError,
                                          'Unexpected type.*str')
 
-    def test_netcdftime_other(self):
-        # Check that cell comparison to a netcdftime.datetime object
+    def test_cftime_other(self):
+        # Check that cell comparison to a cftime.datetime object
         # raises an exception otherwise this will fall back to id comparison
         # producing unreliable results.
-        dt = netcdftime.datetime(2010, 3, 21)
+        dt = cftime.datetime(2010, 3, 21)
         cell = Cell(mock.Mock(timetuple=mock.Mock()))
         self.assert_raises_on_comparison(cell, dt, TypeError,
-                                         'determine the order of netcdftime')
+                                         'determine the order of cftime')
 
     def test_PartialDateTime_bounded_cell(self):
         # Check that bounded comparisions to a PartialDateTime
@@ -81,7 +81,7 @@ def test_PartialDateTime_bounded_cell(self):
     def test_PartialDateTime_unbounded_cell(self):
         # Check that cell comparison works with PartialDateTimes.
         dt = PartialDateTime(month=6)
-        cell = Cell(netcdftime.datetime(2010, 3, 1))
+        cell = Cell(cftime.datetime(2010, 3, 1))
         self.assertLess(cell, dt)
         self.assertGreater(dt, cell)
         self.assertLessEqual(cell, dt)
diff --git a/lib/iris/tests/unit/fileformats/pp_load_rules/test__all_other_rules.py b/lib/iris/tests/unit/fileformats/pp_load_rules/test__all_other_rules.py
index 78b9dfa816..dc30769598 100644
--- a/lib/iris/tests/unit/fileformats/pp_load_rules/test__all_other_rules.py
+++ b/lib/iris/tests/unit/fileformats/pp_load_rules/test__all_other_rules.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2017, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -28,7 +28,7 @@
 
 import numpy as np
 from cf_units import Unit, CALENDAR_GREGORIAN, CALENDAR_360_DAY
-from netcdftime import datetime as nc_datetime
+from cftime import datetime as nc_datetime
 
 import cartopy.crs as ccrs
 import iris
diff --git a/lib/iris/tests/unit/fileformats/pp_load_rules/test__convert_time_coords.py b/lib/iris/tests/unit/fileformats/pp_load_rules/test__convert_time_coords.py
index f531a7a593..f00b39156f 100644
--- a/lib/iris/tests/unit/fileformats/pp_load_rules/test__convert_time_coords.py
+++ b/lib/iris/tests/unit/fileformats/pp_load_rules/test__convert_time_coords.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2017, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -28,7 +28,7 @@
 import iris.tests as tests
 
 from cf_units import Unit, CALENDAR_GREGORIAN
-from netcdftime import datetime as nc_datetime
+from cftime import datetime as nc_datetime
 import numpy as np
 
 from iris.coords import DimCoord, AuxCoord
diff --git a/lib/iris/tests/unit/fileformats/pp_load_rules/test_convert.py b/lib/iris/tests/unit/fileformats/pp_load_rules/test_convert.py
index aa406c8c4b..c1f8bdb891 100644
--- a/lib/iris/tests/unit/fileformats/pp_load_rules/test_convert.py
+++ b/lib/iris/tests/unit/fileformats/pp_load_rules/test_convert.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2017, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -25,7 +25,7 @@
 import iris.tests as tests
 
 import types
-import netcdftime
+import cftime
 
 import cf_units
 import numpy as np
@@ -170,8 +170,8 @@ def test_365_calendar(self):
         f = mock.MagicMock(lbtim=SplittableInt(4, {'ia': 2, 'ib': 1, 'ic': 0}),
                            lbyr=2013, lbmon=1, lbdat=1, lbhr=12, lbmin=0,
                            lbsec=0,
-                           t1=netcdftime.datetime(2013, 1, 1, 12, 0, 0),
-                           t2=netcdftime.datetime(2013, 1, 2, 12, 0, 0),
+                           t1=cftime.datetime(2013, 1, 1, 12, 0, 0),
+                           t2=cftime.datetime(2013, 1, 2, 12, 0, 0),
                            spec=PPField3)
         f.time_unit = six.create_bound_method(PPField3.time_unit, f)
         f.calendar = cf_units.CALENDAR_365_DAY
diff --git a/lib/iris/tests/unit/fileformats/um/fast_load/test__convert_collation.py b/lib/iris/tests/unit/fileformats/um/fast_load/test__convert_collation.py
index 78a9c5b8b5..d164bc5000 100644
--- a/lib/iris/tests/unit/fileformats/um/fast_load/test__convert_collation.py
+++ b/lib/iris/tests/unit/fileformats/um/fast_load/test__convert_collation.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2017, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -24,7 +24,7 @@
 import iris.tests as tests
 
 import cf_units
-import netcdftime
+import cftime
 import numpy as np
 
 from iris.fileformats.um._fast_load \
@@ -78,8 +78,8 @@ def _check_phenomenon(self, metadata, factory=None):
     def test_all_scalar(self):
         field = self._field()
         field.lbtim = 11
-        field.t1 = netcdftime.datetime(1970, 1, 1, 18)
-        field.t2 = netcdftime.datetime(1970, 1, 1, 12)
+        field.t1 = cftime.datetime(1970, 1, 1, 18)
+        field.t2 = cftime.datetime(1970, 1, 1, 12)
         collation = mock.Mock(fields=[field], vector_dims_shape=(),
                               element_arrays_and_dims={})
         metadata = convert_collation(collation)
@@ -99,10 +99,10 @@ def test_all_scalar(self):
     def test_vector_t1(self):
         field = self._field()
         field.lbtim = 11
-        field.t2 = netcdftime.datetime(1970, 1, 1, 12)
-        t1 = ([netcdftime.datetime(1970, 1, 1, 18),
-               netcdftime.datetime(1970, 1, 2, 0),
-               netcdftime.datetime(1970, 1, 2, 6)], [0])
+        field.t2 = cftime.datetime(1970, 1, 1, 12)
+        t1 = ([cftime.datetime(1970, 1, 1, 18),
+               cftime.datetime(1970, 1, 2, 0),
+               cftime.datetime(1970, 1, 2, 6)], [0])
         collation = mock.Mock(fields=[field], vector_dims_shape=(3,),
                               element_arrays_and_dims={'t1': t1})
         metadata = convert_collation(collation)
@@ -125,10 +125,10 @@ def test_vector_t1(self):
     def test_vector_t2(self):
         field = self._field()
         field.lbtim = 11
-        field.t1 = netcdftime.datetime(1970, 1, 1, 18)
-        t2 = ([netcdftime.datetime(1970, 1, 1, 12),
-               netcdftime.datetime(1970, 1, 1, 15),
-               netcdftime.datetime(1970, 1, 1, 18)], [0])
+        field.t1 = cftime.datetime(1970, 1, 1, 18)
+        t2 = ([cftime.datetime(1970, 1, 1, 12),
+               cftime.datetime(1970, 1, 1, 15),
+               cftime.datetime(1970, 1, 1, 18)], [0])
         collation = mock.Mock(fields=[field], vector_dims_shape=(3,),
                               element_arrays_and_dims={'t2': t2})
         metadata = convert_collation(collation)
@@ -153,8 +153,8 @@ def test_vector_t2(self):
     def test_vector_lbft(self):
         field = self._field()
         field.lbtim = 21
-        field.t1 = netcdftime.datetime(1970, 1, 1, 12)
-        field.t2 = netcdftime.datetime(1970, 1, 1, 18)
+        field.t1 = cftime.datetime(1970, 1, 1, 12)
+        field.t2 = cftime.datetime(1970, 1, 1, 18)
         lbft = ([18, 15, 12], [0])
         collation = mock.Mock(fields=[field], vector_dims_shape=(3,),
                               element_arrays_and_dims={'lbft': lbft})
@@ -179,11 +179,11 @@ def test_vector_lbft(self):
     def test_vector_t1_and_t2(self):
         field = self._field()
         field.lbtim = 11
-        t1 = ([netcdftime.datetime(1970, 1, 2, 6),
-               netcdftime.datetime(1970, 1, 2, 9),
-               netcdftime.datetime(1970, 1, 2, 12)], [1])
-        t2 = ([netcdftime.datetime(1970, 1, 1, 12),
-               netcdftime.datetime(1970, 1, 2, 0)], [0])
+        t1 = ([cftime.datetime(1970, 1, 2, 6),
+               cftime.datetime(1970, 1, 2, 9),
+               cftime.datetime(1970, 1, 2, 12)], [1])
+        t2 = ([cftime.datetime(1970, 1, 1, 12),
+               cftime.datetime(1970, 1, 2, 0)], [0])
         collation = mock.Mock(fields=[field], vector_dims_shape=(2, 3),
                               element_arrays_and_dims={'t1': t1, 't2': t2})
         metadata = convert_collation(collation)
diff --git a/lib/iris/tests/unit/fileformats/um/fast_load_structured_fields/test_FieldCollation.py b/lib/iris/tests/unit/fileformats/um/fast_load_structured_fields/test_FieldCollation.py
index bee4f84e97..12168a85d1 100644
--- a/lib/iris/tests/unit/fileformats/um/fast_load_structured_fields/test_FieldCollation.py
+++ b/lib/iris/tests/unit/fileformats/um/fast_load_structured_fields/test_FieldCollation.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2017, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -28,7 +28,7 @@
 import iris.tests as tests
 
 from iris._lazy_data import as_lazy_data
-from netcdftime import datetime
+from cftime import datetime
 import numpy as np
 
 from iris.fileformats.um._fast_load_structured_fields import FieldCollation
diff --git a/lib/iris/tests/unit/plot/test__fixup_dates.py b/lib/iris/tests/unit/plot/test__fixup_dates.py
index ef2f5bb11b..15d154d198 100644
--- a/lib/iris/tests/unit/plot/test__fixup_dates.py
+++ b/lib/iris/tests/unit/plot/test__fixup_dates.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2016, Met Office
+# (C) British Crown Copyright 2016 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -25,7 +25,7 @@
 
 from cf_units import Unit
 import datetime
-import netcdftime
+import cftime
 
 from iris.coords import AuxCoord
 from iris.plot import _fixup_dates
@@ -59,9 +59,9 @@ def test_360_day_calendar(self):
         unit = Unit('days since 2000-02-25 00:00:00', calendar='360_day')
         coord = AuxCoord([3, 4, 5], 'time', units=unit)
         result = _fixup_dates(coord, coord.points)
-        expected_datetimes = [netcdftime.datetime(2000, 2, 28),
-                              netcdftime.datetime(2000, 2, 29),
-                              netcdftime.datetime(2000, 2, 30)]
+        expected_datetimes = [cftime.datetime(2000, 2, 28),
+                              cftime.datetime(2000, 2, 29),
+                              cftime.datetime(2000, 2, 30)]
         self.assertArrayEqual([cdt.datetime for cdt in result],
                               expected_datetimes)
 
@@ -70,9 +70,9 @@ def test_365_day_calendar(self):
         unit = Unit('minutes since 2000-02-25 00:00:00', calendar='365_day')
         coord = AuxCoord([30, 60, 150], 'time', units=unit)
         result = _fixup_dates(coord, coord.points)
-        expected_datetimes = [netcdftime.datetime(2000, 2, 25, 0, 30),
-                              netcdftime.datetime(2000, 2, 25, 1, 0),
-                              netcdftime.datetime(2000, 2, 25, 2, 30)]
+        expected_datetimes = [cftime.datetime(2000, 2, 25, 0, 30),
+                              cftime.datetime(2000, 2, 25, 1, 0),
+                              cftime.datetime(2000, 2, 25, 2, 30)]
         self.assertArrayEqual([cdt.datetime for cdt in result],
                               expected_datetimes)
 
diff --git a/lib/iris/tests/unit/time/test_PartialDateTime.py b/lib/iris/tests/unit/time/test_PartialDateTime.py
index b617eaaa8a..e70aef68fc 100644
--- a/lib/iris/tests/unit/time/test_PartialDateTime.py
+++ b/lib/iris/tests/unit/time/test_PartialDateTime.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2015, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -27,7 +27,7 @@
 import datetime
 import operator
 
-import netcdftime
+import cftime
 
 from iris.tests import mock
 from iris.time import PartialDateTime
@@ -189,14 +189,14 @@ def setUp(self):
         self.op = operator.eq
         self.expected_value = EQ_EXPECTATIONS
 
-    def test_netcdftime_equal(self):
+    def test_cftime_equal(self):
         pdt = PartialDateTime(month=3, microsecond=2)
-        other = netcdftime.datetime(year=2013, month=3, day=20, second=2)
+        other = cftime.datetime(year=2013, month=3, day=20, second=2)
         self.assertTrue(pdt == other)
 
-    def test_netcdftime_not_equal(self):
+    def test_cftime_not_equal(self):
         pdt = PartialDateTime(month=3, microsecond=2)
-        other = netcdftime.datetime(year=2013, month=4, day=20, second=2)
+        other = cftime.datetime(year=2013, month=4, day=20, second=2)
         self.assertFalse(pdt == other)
 
 
@@ -211,14 +211,14 @@ def setUp(self):
         self.op = operator.gt
         self.expected_value = GT_EXPECTATIONS
 
-    def test_netcdftime_greater(self):
+    def test_cftime_greater(self):
         pdt = PartialDateTime(month=3, microsecond=2)
-        other = netcdftime.datetime(year=2013, month=2, day=20, second=3)
+        other = cftime.datetime(year=2013, month=2, day=20, second=3)
         self.assertTrue(pdt > other)
 
-    def test_netcdftime_not_greater(self):
+    def test_cftime_not_greater(self):
         pdt = PartialDateTime(month=3, microsecond=2)
-        other = netcdftime.datetime(year=2013, month=3, day=20, second=3)
+        other = cftime.datetime(year=2013, month=3, day=20, second=3)
         self.assertFalse(pdt > other)
 
 
diff --git a/lib/iris/time.py b/lib/iris/time.py
index b57f7bb6a3..ef02b4dbfc 100644
--- a/lib/iris/time.py
+++ b/lib/iris/time.py
@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2013 - 2015, Met Office
+# (C) British Crown Copyright 2013 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -35,7 +35,7 @@ class PartialDateTime(object):
     Comparisons are defined against any other class with all of the
     attributes: year, month, day, hour, minute, and second.
     Notably, this includes :class:`datetime.datetime` and
-    :class:`netcdftime.datetime`. Comparison also extends to the
+    :class:`cftime.datetime`. Comparison also extends to the
     microsecond attribute for classes, such as
     :class:`datetime.datetime`, which define it.
 
diff --git a/requirements/core.txt b/requirements/core.txt
index 4ed1b174e3..b2dbe52a05 100644
--- a/requirements/core.txt
+++ b/requirements/core.txt
@@ -4,10 +4,11 @@
 # Without these, iris won't even import.
 
 cartopy
+cf_units>=2
+cftime
+dask>=0.17.1
 matplotlib>=2
 netcdf4<1.4
 numpy>=1.14
-scipy
 # pyke (not pip installable)  #conda: pyke
-cf_units>=2
-dask>=0.17.1
+scipy