The late Paul Richey (ex 1(F) in the Battle of France) was extremely excised by 'Piece of Cake' since he felt that there were a number of similarities to his Fighter Pilot . He was embarking upon a court case against Robinson over breach of copyright at the time of his death, and his wife continued the case, although I don't know the outcome.
There are some striking similarities, of course - a character with the nickname of 'Moggy' in PoC, a real character nicknamed 'Pussy' in Paul Richey's book. If you've not already read it, suggest that you have a look and compare it with the book or the TV series.