Accounts vary as to the source of the name, but our best information goes as follows: There was once a veteran BBC writer/producer named Barry Took, who 'took' under his wing a group of five wet-behind-the-ears British comedy writer-performers, and one wide-eyed innocent American animator to form a new BBC comedy show in the spring of 1969. Cleese and Chapman had done 'At Last the 1948 Show,' and Idle, Palin, Jones and Gilliam had done 'Do Not Adjust Your Set,' which were nice shows but rather traditional, and black-and-white, so forget them. One of Barry's nicknames around the water cooler was 'Baron von Took', so this proposed new show became known in sniggering internal BBC memos as 'Baron von Took's Flying Circus' (a reference to WWI German air ace Baron von Richtofen's Flying Circus). This seemed appropriate as the planned show soon became notorious for being uncontrollable. The future Pythons themselves wanted it called something different every week, an idea echoed at the end of each first series episode.
Spring turned to summer, the show was officially signed up by the BBC, and a real title was needed.'Whither Canada?', 'Owl-Stretching Time', 'Bunn, Wackett, Buzzard, Stubble, and Boot', 'It's', 'It,' 'The Venus Di Milo Panic Show,' 'The Toad Elevating Moment,' and 'A Horse, a Basin, a Bucket and a Spoon' were all rejected. They decided to keep the 'Flying Circus' suffix because that's what everyone had been calling it anyway, and by this point the BBC wouldn't let them call it anything else. They went through a variety of names for whose Flying Circus it was ('Cynthia Fellatio's Flying Circus' was considered). Michael Palin had seen the name 'Gwen Dibley' in a women's journal and wanted that used, but as it was a real person the idea was nixed. Somehow someone (probably John Cleese) thought of 'Python'. Then 'Norm Python' and 'Bob Python' came and went. The 'Monty' is mysterious, but it is said that Eric Idle dredged up a memory from his local pub, where a small man in a suit and bow tie would always come in and ask everyone 'Has Monty been in yet?' It conjured up an image of a seedy, sixth-rate theatrical booker, sitting in a darkened corner of the pub. Monty was a sharp kind of name, and combined with 'Python' it became suddenly unusually pleasing and resonant. Thus began 'MONTY PYTHON'S FLYING CIRCUS.' Most of the other names were used eventually. The name of Gwen Dibley popped up fairly often, and before each show a ragged old man called out 'It's.' Most of the others got to be the show's title for one episode each in the first series