Fifteen months before the BBC visited the set in May 1974, the Monty Python troupe assembled the first version of the screenplay. When half of the resulting material was set in the Middle Ages, and half was set in the present day, the group opted to focus on the Middle Ages, revolving on the legend of the Holy Grail. By the fourth or fifth version of their screenplay, the story was complete, and the cast joked the fact that the Grail was never retrieved would be "a big let-down ... a great anti-climax". Graham Chapman said a challenge was incorporating scenes that did not fit the Holy Grail motif.
Neither Terry Gilliam nor Terry Jones had directed a film before, and described it as a learning experience in which they would learn to make a film by making an entire full-length film. The cast humorously described the novice directing style as employing the level of mutual disrespect always found in Monty Python's work.
The film’s initial budget of approximately £200,000 was raised by convincing 10 separate investors to contribute £20,000 apiece. Three of those investors were the rock bands Pink Floyd, Led Zeppelin, and Genesis, who were persuaded to help fund the film by Tony Stratton-Smith, head of Charisma Records (the record label that released Python’s early comedy albums). According to Terry Gilliam, the Pythons turned to rock stars like Pink Floyd, Led Zeppelin and Elton John for finance as the studios refused to fund the film and rock stars saw it as "a good tax write-off" due to UK income tax being "as high as 90%" at the time.