diff --git a/lib/iris/coord_systems.py b/lib/iris/coord_systems.py
index 1f755998b1..bc2399d149 100644
--- a/lib/iris/coord_systems.py
+++ b/lib/iris/coord_systems.py
@@ -124,6 +124,7 @@ def as_cartopy_projection(self):
 
 _short_datum_names = {
     "OSGB 1936": "OSGB36",
+    "OSGB_1936": "OSGB36",
     "WGS 84": "WGS84",
 }
 
diff --git a/lib/iris/tests/integration/test_netcdf.py b/lib/iris/tests/integration/test_netcdf.py
index 8c913a1043..57343de68a 100644
--- a/lib/iris/tests/integration/test_netcdf.py
+++ b/lib/iris/tests/integration/test_netcdf.py
@@ -628,7 +628,6 @@ def test_no_load_datum_cf_var(self):
 
     def test_save_datum(self):
         expected = "OSGB 1936"
-        # saved_crs = iris.coord_systems.GeogCS.from_datum(datum="OSGB36")
         saved_crs = iris.coord_systems.Mercator(
             ellipsoid=iris.coord_systems.GeogCS.from_datum("OSGB36")
         )