diff --git a/Tests/test_geocode.py b/Tests/test_geocode.py
index cbd2e18..9bde6cc 100644
--- a/Tests/test_geocode.py
+++ b/Tests/test_geocode.py
@@ -37,7 +37,7 @@ def test_force_setup(self):
             geo.force_setup()
         cache_dir = geo.cache_manager.cache_dir
         assert cache_dir.is_dir()
-        assert len([c for c in cache_dir.glob("*.p") if "gmaps" not in c.name]) == 14
+        assert len([c for c in cache_dir.glob("*.p") if "gmaps" not in c.name]) == 15
 
     def test_geocode_llsoa(self):
         """
diff --git a/geocode/neso.py b/geocode/neso.py
index c0f9d62..1f8a7d1 100644
--- a/geocode/neso.py
+++ b/geocode/neso.py
@@ -40,7 +40,6 @@ def __init__(self, cache_manager, proxies=None, ssl_verify=True):
         """The NESO data manager for the Geocode class."""
         self.cache_manager = cache_manager
         self.gsp_lookup_20181031_cache_file = "gsp_lookup_20181031"
-        self.gsp_boundaries_20250109_cache_file = "gsp_boundaries_20250109"
         self.gsp_boundaries_20220314_cache_file = "gsp_boundaries_20220314"
         self.gsp_boundaries_20181031_cache_file = "gsp_boundaries_20181031"
         self.dno_boundaries_cache_file = "dno_boundaries"
@@ -55,8 +54,8 @@ def force_setup(self):
         """
         Function to setup lookup files.
         """
-        self.load_gsp_boundaries("20220314")
-        self.load_gsp_boundaries("20250109")
+        for version in ["20220314", "20250109", "20251204"]:
+            self.load_gsp_boundaries(version)
         self._load_dno_boundaries()
 
     def _load_gsp_lookup_20181031(self):
@@ -95,36 +94,43 @@ def _load_gsp_lookup_20181031(self):
         )
         return gsp_lookup
 
-    def _load_gsp_boundaries_20250109(self):
+    def _load_gsp_boundaries(self, version: str):
         """
-        Load the 20250109 GSP / GNode boundaries, either from local cache if available, else fetch
+        Generic function to load latest GSP / GNode boundaries, either from local cache if available, else fetch
         from ESO Data Portal API.
 
+        Parameters
+        ----------
+        `version` : str
+            The version of the GSP boundaries to load.
+
         Returns
         -------
         gsp_regions: GeoPandas.GeoDataFrame
             A geodataframe of MultiPolygons for the GSP boundaries.
         """
+        data_url = {
+            "20250109": "https://api.neso.energy/dataset/2810092e-d4b2-472f-b955-d8bea01f9ec0/resource/d95e8c1b-9cd9-41dd-aacb-4b53b8c07c20/download/gsp_regions_20250109.zip",
+            "20251204": "https://api.neso.energy/dataset/2810092e-d4b2-472f-b955-d8bea01f9ec0/resource/c5647312-afab-4a58-8158-2f1efed1d7fc/download/gsp_regions_20251204.zip",
+        }
         gsp_boundaries_cache_contents = self.cache_manager.retrieve(
-            self.gsp_boundaries_20250109_cache_file
+            f"gsp_boundaries_{version}"
         )
         if gsp_boundaries_cache_contents is not None:
             logging.debug(
-                "Loading 20250109 GSP boundaries from cache ('%s')",
-                self.gsp_boundaries_20250109_cache_file,
+                f"Loading {version} GSP boundaries from cache gsp_boundaries_{version}",
             )
             return gsp_boundaries_cache_contents
         logging.info(
-            "Extracting the 20250109 GSP boundary data from NESO's Data Portal API (this "
+            f"Extracting the {version} GSP boundary data from NESO's Data Portal API (this "
             "only needs to be done once)"
         )
-        eso_url = "https://api.neso.energy/dataset/2810092e-d4b2-472f-b955-d8bea01f9ec0/resource/d95e8c1b-9cd9-41dd-aacb-4b53b8c07c20/download/gsp_regions_20250109.zip"
         success, api_response = utils.fetch_from_api(
-            eso_url, proxies=self.proxies, ssl_verify=self.ssl_verify
+            data_url[version], proxies=self.proxies, ssl_verify=self.ssl_verify
         )
         if success:
             zip_file = io.BytesIO(api_response.content)
-            target_file = "Proj_27700/GSP_regions_27700_20250109.geojson"
+            target_file = f"Proj_27700/GSP_regions_27700_{version}.geojson"
             with ZipFile(zip_file, "r") as zip_ref:
                 if target_file in zip_ref.namelist():
                     with zip_ref.open(target_file) as file:
@@ -135,12 +141,11 @@ def _load_gsp_boundaries_20250109(self):
                         gsp_regions.geometry = gsp_regions.buffer(0)
         else:
             raise utils.GenericException(
-                "Encountered an error while extracting GSP region data from ESO " "API."
+                "Encountered an error while extracting GSP region data from ESO API."
             )
-        self.cache_manager.write(self.gsp_boundaries_20250109_cache_file, gsp_regions)
+        self.cache_manager.write(f"gsp_boundaries_{version}", gsp_regions)
         logging.info(
-            "20250109 GSP boundaries extracted and pickled to '%s'",
-            self.gsp_boundaries_20250109_cache_file,
+            f"{version} GSP boundaries extracted and pickled to gsp_boundaries_{version}",
         )
         return gsp_regions
 
@@ -202,10 +207,10 @@ def load_gsp_boundaries(self, version: str):
         gsp_regions: GeoPandas.GeoDataFrame
             A geodataframe of MultiPolygons for the GSP boundaries.
         """
-        if version == "20250109":
-            return self._load_gsp_boundaries_20250109()
-        elif version == "20220314":
+        if version == "20220314":
             return self._load_gsp_boundaries_20220314()
+        elif version in ["20250109", "20251204"]:
+            return self._load_gsp_boundaries(version=version)
         else:
             raise ValueError(f"GSP boundaries version {version} is not supported.")