Neil's involvement with members of the Python team dates back to before the Flying Circus started. As a member of the Bonzo Dog (Doo Dah) Band , Neil appeared with Michael, Eric, Terry G and Terry J on Do Not Adjust Your Set , a 1960s children's television programme. When the Bonzos split up, Neil gravitated toward Python. He wrote the music for the songs that appeared in Holy Grail and also appeared in the film as Sir Robin's minstrel. After the film, John Cleese left the group to work on Fawlty Towers . As a result, the group's working practices changed slightly for their fourth television series, and Neil wrote some music for the team, as well as co-writing a couple of sketches.

Neil's standing as an 'associate Python' was increased when he appeared in the stage shows in London, New York and at the Hollywood Bowl. As well as joining in some Python sketches, including the 'Lumberjack Song' and 'Election Night Special', Neil also performed some of his own songs, including 'How Sweet to be an Idiot' and 'The Urban Spaceman'.

Outside of Python, Neil continued to work with Eric Idle, most notably