diff --git a/app/main.py b/app/main.py
index 63185ff..b17bfa7 100644
--- a/app/main.py
+++ b/app/main.py
@@ -35,7 +35,19 @@ PRICES_URL = os.environ.get("FUEL_API_PRICES_URL", "https://api.fuelfinder.servi
 CACHE_TTL = int(os.environ.get("FUEL_CACHE_TTL", "300"))       # seconds (5 min)
 TOKEN_EXPIRY_BUFFER = int(os.environ.get("FUEL_TOKEN_BUFFER", "60"))  # seconds
 
-DEMO_MODE = not (CLIENT_ID and CLIENT_SECRET)
+# Public full-UK mirror of the Fuel Finder dataset (GitHub Actions, hourly),
+# used as the default source when OAuth credentials are not configured.
+# Licence: Open Government Licence v3.0. No auth required.
+CSV_URL = os.environ.get(
+    "FUEL_CSV_URL",
+    "https://raw.githubusercontent.com/matthewgall/fuelfinder-archive/main/data.csv",
+)
+CSV_REFRESH_TTL = int(os.environ.get("FUEL_CSV_TTL", "3600"))  # seconds (1h)
+
+# Source selection: "auto" (CSV if no creds, API if creds), "csv", "api"
+SOURCE = os.environ.get("FUEL_SOURCE", "auto").lower()
+
+DEMO_MODE = not (CLIENT_ID and CLIENT_SECRET) and SOURCE != "csv"
 
 # ---------------------------------------------------------------------------
 # In-memory cache state
@@ -49,9 +61,63 @@ _state = {
     "last_error": None,
     "sync_attempts": 0,
     "sync_failures": 0,
+    "source_used": None,
 }
 
 
+def _parse_csv_to_stations(text: str) -> list:
+    """Parse the Fuel Finder archive CSV into a station list.
+
+    Header uses dotted keys: forecourts.trading_name, forecourts.location.latitude,
+    forecourts.fuel_price.E10, forecourts.price_change_effective_timestamp.E10, etc.
+    """
+    import csv
+    import io
+
+    reader = csv.DictReader(io.StringIO(text))
+    stations = []
+    for row in reader:
+        def num(key):
+            try:
+                val = row.get(key)
+                return float(val) if val not in (None, "") else None
+            except (TypeError, ValueError):
+                return None
+
+        lat = num("forecourts.location.latitude")
+        lng = num("forecourts.location.longitude")
+        prices = {}
+        for grade, label in (("E5", "E5"), ("E10", "E10"), ("B7S", "DIESEL"), ("B7P", "DIESEL")):
+            p = num(f"forecourts.fuel_price.{grade}")
+            if p is not None and grade not in prices:
+                prices[label] = p
+        stations.append({
+            "id": row.get("forecourts.node_id"),
+            "name": row.get("forecourts.trading_name"),
+            "brand": row.get("forecourts.brand_name"),
+            "address": (row.get("forecourts.location.address_line_1") or "") + " " + (row.get("forecourts.location.address_line_2") or ""),
+            "postcode": row.get("forecourts.location.postcode"),
+            "lat": lat,
+            "lng": lng,
+            "prices": prices,
+            "price_updated": row.get("forecourts.price_change_effective_timestamp.E10")
+                          or row.get("forecourts.price_change_effective_timestamp.E5"),
+            "is_motorway": row.get("forecourts.is_motorway_service_station") == "true",
+        })
+    return stations
+
+
+def _fetch_csv() -> list:
+    """Download the hourly full-UK CSV mirror."""
+    with httpx.Client(timeout=120) as client:
+        resp = client.get(CSV_URL)
+        resp.raise_for_status()
+        stations = _parse_csv_to_stations(resp.text)
+        if not stations:
+            raise RuntimeError("CSV parse returned zero stations")
+        return stations
+
+
 def _get_token(client: httpx.Client) -> str:
     """Return a valid bearer token, refreshing via client-credentials grant."""
     if _state["token"] and time.time() < _state["token_expires_at"] - TOKEN_EXPIRY_BUFFER:
@@ -88,10 +154,19 @@ def _refresh_cache() -> None:
     """Refresh the station cache if stale (or on first run)."""
     _state["sync_attempts"] += 1
     try:
-        if DEMO_MODE:
-            raise RuntimeError("Fuel Finder credentials not configured (FUEL_API_CLIENT_ID/SECRET)")
-        data = _fetch_prices()
-        _state["stations"] = data
+        if SOURCE == "csv":
+            _state["stations"] = _fetch_csv()
+            _state["source_used"] = "csv"
+        elif SOURCE == "api":
+            _state["stations"] = _fetch_prices()
+            _state["source_used"] = "api"
+        else:  # auto: API if creds present, otherwise public CSV
+            if not DEMO_MODE:
+                _state["stations"] = _fetch_prices()
+                _state["source_used"] = "api"
+            else:
+                _state["stations"] = _fetch_csv()
+                _state["source_used"] = "csv"
         _state["stations_fetched_at"] = time.time()
         _state["last_error"] = None
     except Exception as exc:  # keep serving stale cache on failure
@@ -101,8 +176,9 @@ def _refresh_cache() -> None:
 
 @asynccontextmanager
 async def lifespan(_: FastAPI):
-    if not DEMO_MODE:
-        _refresh_cache()
+    # Always try to warm the cache. In auto mode with no credentials this
+    # fetches the public full-UK CSV; with credentials it uses the OAuth API.
+    _refresh_cache()
     yield
 
 
@@ -183,22 +259,13 @@ def stations(
     radius: float = Query(20.0, description="Search radius in km"),
     limit: int = Query(10, ge=1, le=100),
 ):
-    if DEMO_MODE:
-        return JSONResponse(
-            status_code=503,
-            content={
-                "error": "Fuel Finder credentials not configured on the relay",
-                "hint": "Set FUEL_API_CLIENT_ID and FUEL_API_CLIENT_SECRET (see README)",
-            },
-        )
+    if _state["stations"] is None:
+        raise HTTPException(status_code=502, detail="No data cached yet and upstream fetch failed")
 
     # Trigger a refresh if stale; keep serving stale cache if it fails.
     if time.time() - _state["stations_fetched_at"] > CACHE_TTL:
         _refresh_cache()
 
-    if _state["stations"] is None:
-        raise HTTPException(status_code=502, detail="No data cached yet and upstream fetch failed")
-
     rows = []
     for station in _stations_list():
         price = _fuel_price(station, fuel)