n the mid-1970s, Innes became closely associated with the Monty Python team, having first worked with Michael Palin, Terry Jonesand Eric Idle on the 1960s television show Do Not Adjust Your Set. He contributed music to the Monty Python albums Monty Python's Previous Record (1972) and The Monty Python Matching Tie and Handkerchief (1973), and played a major role in performing and writing songs and sketches for their final TV series in 1974, after John Cleese temporarily left the troupe. He wrote a squib of a song called "George III" for the episode "The Golden Age of Ballooning", which was sung by the Flirtations but billed onscreen as the Ronettes. He also wrote the song "When Does a Dream Begin?", used in "Anything Goes: The Light Entertainment War". He co-wrote the "Most Awful Family in Britain" sketch and played a humorous stilted guitar version of the theme song, "The Liberty Bell" march, during the credits of the last episode, "Party Political Broadcast". He is one of only two non-Pythons ever to be credited writers for the TV series, the other being Douglas Adams (who co-wrote the "Patient Abuse" sketch, also featured in "Party Political Broadcast").
He appeared on stage with the Pythons in the UK and Canada in 1973, in London in 1974 and in New York City in 1976, performing the Bob Dylanesque "Protest Song" (complete with harmonica) on the album Monty Python Live at City Center. He was introduced as Raymond Scum. After his introduction he told the audience, "I've suffered for my music. Now it's your turn." In 1980, he travelled to the States with the Pythons again, subsequently appearing in Monty Python Live at the Hollywood Bowl. He performed the songs "How Sweet to Be an Idiot" and "I'm the Urban Spaceman". He also appeared as one of the singing "Bruces" in the Philosopher Sketch and as a Church Policeman in the "Salvation Fuzz" sketch.
Innes wrote original songs for the film Monty Python and the Holy Grail (1975), such as "Knights of the Round Table" and "Brave Sir Robin". He appeared in the film as a head-bashing monk, the serf crushed by the giant wooden rabbit, and the leader of Sir Robin's minstrels. He also had small roles in Terry Gilliam's Jabberwocky (1977) and Monty Python's Life of Brian (1979), and performed the whistling on the latter's hit song, "Always Look on the Bright Side of Life".[10] His collaborations with Monty Python and other artists were documented in the musical film The Seventh Python (2008), which premiered at the Mods & Rockers Film Festival on 26 June 2008