 Three episodes of this series no longer exist, after an archive  purge at the BBC in the 70s saw the destruction of the only known  copies. Until recently, there were five missing episodes until an  appeal by the BBC called "Treasure Hunt" saw the return of two 16mm  film recordings taken from the original video tapes. These  recordings had been dumped in a skip outside the Elstree Studios  when they were found and taken home by one of the studio staff, 30  years ago. After seeing the Treasure Hunt appeal on TV in 2001,  the prints were returned by a friend of the staff member, to whom  the prints had been entrusted.