Page showing the problem:
https://en.wikipedia.org/wiki/Great_Lines_Heritage_Park
Map shows:
Map should show:
Roughly the result of this template:
{{Infobox mapframe |coord={{Coord|51.385|N|0.537|E|type:landmark|display=title, inline}}}}
Oddly enough, the map is perfectly centered on another park, just 30 miles away from the given coordinates; caching issue?
Other steps taken:
Infobox mapframe produces the correct results, so it doesn't appear to be the culprit. ?action=purge does nothing.