diff --git a/tests/functional/xtriggers/04-sequential.t b/tests/functional/xtriggers/04-sequential.t
new file mode 100644
index 00000000000..a4733bf437a
--- /dev/null
+++ b/tests/functional/xtriggers/04-sequential.t
@@ -0,0 +1,104 @@
+#!/usr/bin/env bash
+# THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
+# Copyright (C) NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test xtrigger sequential spawning -
+#   
+
+. "$(dirname "$0")/test_header"
+
+set_test_number 7
+
+# Test workflow uses built-in 'echo' xtrigger.
+init_workflow "${TEST_NAME_BASE}" << '__FLOW_CONFIG__'
+[scheduler]
+    cycle point format = %Y
+    allow implicit tasks = True
+[scheduling]
+    initial cycle point = 3000
+    runahead limit = P5
+    sequential xtriggers default = True
+    [[xtriggers]]
+        clock_1 = wall_clock(offset=P2Y, sequential=False)
+        clock_2 = wall_clock()
+        up_1 = workflow_state(\
+            workflow=%(workflow)s, \
+            task=b, \
+            point=%(point)s, \
+            offset=-P1Y, \
+            sequential=False \
+        ):PT1S
+    [[graph]]
+        R1 = """
+@clock_1 => a
+b
+"""
+        +P1Y/P1Y = """
+@clock_2 => a
+@clock_2 => b
+@up_1 => c
+"""
+__FLOW_CONFIG__
+
+run_ok "${TEST_NAME_BASE}-val" cylc validate "${WORKFLOW_NAME}"
+
+# Run workflow; it will stall waiting on the never-satisfied xtriggers.
+cylc play "${WORKFLOW_NAME}"
+
+poll_grep_workflow_log -E '3001/c .* => succeeded'
+
+cylc show "${WORKFLOW_NAME}//3001/a" | grep -E 'state: ' > 3001.a.log
+cylc show "${WORKFLOW_NAME}//3002/a" 2>&1 >/dev/null \
+    | grep -E 'No matching' > 3002.a.log
+
+# 3001/a should be spawned at both 3000/3001.
+cmp_ok 3001.a.log - <<__END__
+state: waiting
+__END__
+# 3002/a should not exist.
+cmp_ok 3002.a.log - <<__END__
+No matching active tasks found: 3002/a
+__END__
+
+
+cylc show "${WORKFLOW_NAME}//3001/b" | grep -E 'state: ' > 3001.b.log
+cylc show "${WORKFLOW_NAME}//3002/b" 2>&1 >/dev/null \
+    | grep -E 'No matching' > 3002.b.log
+
+# 3001/b should be only at 3001.
+cmp_ok 3001.b.log - <<__END__
+state: waiting
+__END__
+cmp_ok 3002.b.log - <<__END__
+No matching active tasks found: 3002/b
+__END__
+
+
+cylc show "${WORKFLOW_NAME}//3002/c" | grep -E 'state: ' > 3002.c.log
+cylc show "${WORKFLOW_NAME}//3005/c" | grep -E 'state: ' > 3005.c.log
+
+# c should be from 3002-3005.
+cmp_ok 3002.c.log - <<__END__
+state: waiting
+__END__
+cmp_ok 3005.c.log - <<__END__
+state: waiting
+__END__
+
+
+cylc stop --now --max-polls=10 --interval=2 "${WORKFLOW_NAME}"
+purge
+exit