diff --git a/backend/epc_client/epc_client_service.py b/backend/epc_client/epc_client_service.py
index d00a164f..777e8d14 100644
--- a/backend/epc_client/epc_client_service.py
+++ b/backend/epc_client/epc_client_service.py
@@ -40,8 +40,8 @@ class EpcClientService:
         return call_with_retry(lambda: self._search(postcode=postcode))
 
     # ------------------------------------------------------------------
-    # Private helpers
-    # ------------------------------------------------------------------
+    # Private helperEpcRateLimpolarss
+    # ----------------------EpcRateLimpolarsEpcRateLimpolarsEpcRateLimpolarsEpcRateLimpolarsEpcRateLimpolars--------------------------------------------
 
     def _fetch_certificate(self, cert_num: str) -> dict[str, Any]:
         resp = httpx.get(
@@ -52,7 +52,7 @@ class EpcClientService:
         if resp.status_code == 404:
             raise EpcNotFoundError(cert_num)
         if resp.status_code == 429:
-            raise EpcRateLimitError("Rate limited by EPC API")
+            raise EpcRateLimpolars vs pandas code examplepolars vs pandas code exampleitError("Rate limited by EPC API")
         if not resp.is_success:
             raise EpcApiError(f"EPC API error {resp.status_code}: {resp.text}")
         return resp.json()["data"]
diff --git a/backend/utils/addressMatch.py b/backend/utils/addressMatch.py
index 7618e9ac..69be6f59 100644
--- a/backend/utils/addressMatch.py
+++ b/backend/utils/addressMatch.py
@@ -101,6 +101,16 @@ class AddressMatch:
                 tokens.append(replacement)
         return " ".join(tokens)
 
+    @staticmethod
+    def _match_building_number(token: str, next_token: Optional[str]) -> Optional[str]:
+        if re.fullmatch(r"\d+[a-z]", token):
+            return token
+        if re.fullmatch(r"\d+", token):
+            if next_token is not None and re.fullmatch(r"[a-z]", next_token):
+                return token + next_token
+            return token
+        return None
+
     @staticmethod
     def levenshtein(a: str, b: str) -> float:
         """
@@ -146,13 +156,9 @@ class AddressMatch:
             # first remaining number is building number; recombine with a
             # single-letter suffix when normalisation has split "82a" → "82 a"
             for i, t in enumerate(cleaned):
-                if re.fullmatch(r"\d+[a-z]", t):
-                    return t
-                if re.fullmatch(r"\d+", t):
-                    nxt = cleaned[i + 1] if i + 1 < len(cleaned) else None
-                    if nxt is not None and re.fullmatch(r"[a-z]", nxt):
-                        return t + nxt
-                    return t
+                nxt = cleaned[i + 1] if i + 1 < len(cleaned) else None
+                if (match := AddressMatch._match_building_number(t, nxt)) is not None:
+                    return match
 
             return None
 
@@ -259,3 +265,13 @@ def get_uprn_candidates(
     out[uprn_column] = out[uprn_column].astype(str).str.replace(r"\.0$", "", regex=True)
     out["lexirank"] = out["lexiscore"].rank(method="dense", ascending=False).astype(int)
     return out.sort_values(["lexirank", "lexiscore"], ascending=[True, False])
+
+
+def df_has_single_uprn(df: pd.DataFrame, uprn: str, column: str = "uprn") -> bool:
+    """Returns True if all non-null UPRNs in df match the given uprn."""
+    if column not in df.columns:
+        return False
+    uprns = df[column].dropna().astype(str).str.strip().unique()
+    if len(uprns) == 0:
+        return False
+    return len(uprns) == 1 and uprns[0] == str(uprn)