diff --git a/app/broadcast_areas/models.py b/app/broadcast_areas/models.py
index 8d364e3c5..ddd163a53 100644
--- a/app/broadcast_areas/models.py
+++ b/app/broadcast_areas/models.py
@@ -203,8 +203,8 @@ class CustomBroadcastArea(BaseBroadcastArea):
 class CustomBroadcastAreas(SerialisedModelCollection):
     model = CustomBroadcastArea
 
-    def __init__(self, *, area_ids, polygons):
-        self.items = area_ids
+    def __init__(self, *, names, polygons):
+        self.items = names
         self._polygons = polygons
 
     def __getitem__(self, index):
diff --git a/app/models/broadcast_message.py b/app/models/broadcast_message.py
index 5e1a5deb4..247edc478 100644
--- a/app/models/broadcast_message.py
+++ b/app/models/broadcast_message.py
@@ -89,10 +89,9 @@ class BroadcastMessage(JSONModel):
 
     @property
     def areas(self):
-        polygons = self._dict['areas']['simple_polygons']
-        library_areas = self.get_areas(self.area_ids)
+        if 'ids' in self._dict['areas']:
+            library_areas = self.get_areas(self.area_ids)
 
-        if library_areas:
             if len(library_areas) != len(self.area_ids):
                 raise RuntimeError(
                     f'BroadcastMessage has {len(self.area_ids)} areas '
@@ -101,8 +100,8 @@ class BroadcastMessage(JSONModel):
             return library_areas
 
         return CustomBroadcastAreas(
-            area_ids=self.area_ids,
-            polygons=polygons,
+            names=self._dict['areas']['names'],
+            polygons=self._dict['areas']['simple_polygons'],
         )
 
     @property
diff --git a/tests/__init__.py b/tests/__init__.py
index 95bd17233..8c9d5ad12 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -678,6 +678,7 @@ def broadcast_message_json(
     updated_at=None,
     approved_by_id=None,
     cancelled_by_id=None,
+    areas=None,
     area_ids=None,
     simple_polygons=None,
     content=None,
@@ -696,7 +697,7 @@ def broadcast_message_json(
         'reference': reference,
 
         'personalisation': {},
-        'areas': {
+        'areas': areas or {
             'ids': area_ids or ['ctry19-E92000001', 'ctry19-S92000003'],
             'simple_polygons': simple_polygons or [],
         },
diff --git a/tests/app/broadcast_areas/test_utils.py b/tests/app/broadcast_areas/test_utils.py
index 8ed121995..c372aa2e4 100644
--- a/tests/app/broadcast_areas/test_utils.py
+++ b/tests/app/broadcast_areas/test_utils.py
@@ -175,8 +175,10 @@ def test_aggregate_areas_for_custom_polygons(
 ):
     broadcast_message = BroadcastMessage(
         broadcast_message_json(
-            area_ids=['derived from polygons'],
-            simple_polygons=simple_polygons
+            areas={
+                'names': [f'polygon {i}' for i, _ in enumerate(simple_polygons)],
+                'simple_polygons': simple_polygons
+            }
         )
     )
 
diff --git a/tests/app/main/views/test_broadcast.py b/tests/app/main/views/test_broadcast.py
index e50b0a858..3c13b281c 100644
--- a/tests/app/main/views/test_broadcast.py
+++ b/tests/app/main/views/test_broadcast.py
@@ -974,8 +974,10 @@ def test_preview_broadcast_areas_page_with_custom_polygons(
             created_by_id=fake_uuid,
             service_id=SERVICE_ONE_ID,
             status='draft',
-            area_ids=['Area one', 'Area two', 'Area three'],
-            simple_polygons=polygons,
+            areas={
+                'names': ['Area one', 'Area two', 'Area three'],
+                'simple_polygons': polygons,
+            }
         ),
     )
     client_request.login(active_user_create_broadcasts_permission)
diff --git a/tests/app/models/test_broadcast_message.py b/tests/app/models/test_broadcast_message.py
index 9b2dd3862..423bf2db2 100644
--- a/tests/app/models/test_broadcast_message.py
+++ b/tests/app/models/test_broadcast_message.py
@@ -38,6 +38,22 @@ def test_content_comes_from_attribute_not_template():
     assert broadcast_message.content == 'This is a test'
 
 
+@pytest.mark.parametrize(('areas', 'expected_length'), [
+    ({'ids': []}, 0),
+    ({'ids': ['wd20-E05009372']}, 1),
+    ({'names': ['somewhere'], 'simple_polygons': [[[3.5, 1.5]]]}, 1)
+])
+def test_areas(
+    areas,
+    expected_length
+):
+    broadcast_message = BroadcastMessage(broadcast_message_json(
+        areas=areas
+    ))
+
+    assert len(list(broadcast_message.areas)) == expected_length
+
+
 def test_areas_raises_for_missing_areas():
     broadcast_message = BroadcastMessage(broadcast_message_json(
         area_ids=[