diff --git a/docs/src/whatsnew/latest.rst b/docs/src/whatsnew/latest.rst
index c5cd961679..9564863d1b 100644
--- a/docs/src/whatsnew/latest.rst
+++ b/docs/src/whatsnew/latest.rst
@@ -102,6 +102,9 @@ This document explains the changes made to Iris for this release
 #. `@trexfeathers`_ adapted benchmarking to work with ASV ``>=v0.6`` by no
    longer using the ``--strict`` argument. (:pull:`5496`)
 
+#. `@fazledyn-or`_ replaced ``NotImplementedError`` with ``NotImplemented`` as
+   a proper method call. (:pull:`5544`)
+
 
 .. comment
     Whatsnew author names (@github name) in alphabetical order. Note that,
@@ -109,6 +112,7 @@ This document explains the changes made to Iris for this release
 
 .. _@scottrobinson02: https://github.com/scottrobinson02
 .. _@acchamber: https://github.com/acchamber
+.. _@fazledyn-or: https://github.com/fazledyn-or
 
 
 .. comment
diff --git a/lib/iris/coords.py b/lib/iris/coords.py
index 3ff9bc8e5e..d5ee2667d8 100644
--- a/lib/iris/coords.py
+++ b/lib/iris/coords.py
@@ -3119,7 +3119,7 @@ def __str__(self):
 
     def __add__(self, other):
         # Disable the default tuple behaviour of tuple concatenation
-        raise NotImplementedError()
+        return NotImplemented
 
     def xml_element(self, doc):
         """