"Mastermind" first aired on BBC1 in 1972 and lasted until 1997. It was presented by Magnus Magnusson. It was originally broadcast late on a Sunday night and was not expected to receive a huge audience. In 1973 it was moved to a prime-time slot as an emergency replacement for a Leslie Phillips sitcom, "Casanova '73", which had been moved to a later time following complaints about its risqué content. The quiz subsequently became one of the most-watched shows on British television. Magnusson's catchphrase "I've started so I'll finish" was also the title of his history of the show. The original series was filmed in academic or ecclesiastical buildings. The last programme of the original series was filmed at St Magnus Cathedral in Orkney.