I remember seeing a TV play, possibly in the 60s or 70s in which an elderly nanny arrives to look after 2 children. She takes them on an outing to see the Crystal Palace (not the football team!) and is shocked to discover that it is no longer there, having burnt down 30 or 40 years previously. From this we discover she is a ghost. Can't remember anything else but I fancy the lead actress was Flora Robson or some other distinguished veteran.