Er, well actually, John Cleese and Graham Chapman were so embarrassed by the film they had their names removed from the credits.
Apparently so much of their script was altered they disowned the film.
I think only the 'additional material by John Wells and John Fortune' credit exists.
As bad as some people think the film is, it's definitely worth a watch. The story is quirky, but has many treasurable scenes and is great fun.
The outstanding cast of James Booth, Richard Briers, Ronald Fraser, Donald Sinden, Kenneth Cope, John Wells, Richard Beckinsale, Michael Bentine, Spike Milligan, Derek Griffiths and Penelope Keith ensure fine performances.