Time for some clues.
Mrs Stewie and myself went for a walk earlier this year and using our Ringo app to pay for our car parking, followed the course of a river passing a temporarily closed train station serving a recreational area which has been a popular attraction with families for many years. The building itself is not visible on street view, but took our attention and Mrs Stewie photographed it suggesting it could be used on GTP.
Unfortunately , we do not know a lot about the building and was rather hoping someone else would!