The script for Monty Python and The Holy Grail was sent to the BBFC for advice in 1974.

The classification X was advised, meaning that no one younger than 18 would be able to view the film if it was made in line with the script. The defining issues included very strong language and crude sex references. The BBFC also advised the company what changes would need to be made to receive an AA classification (meaning no persons under 14 would be able to view the film) and what additional changes would need to be made to receive an A classification (which would allow anyone to see the film but with parents advised that film may be unsuitable for young children).

In late 1974, the BBFC saw an unfinished 'rough cut' of the film for advice. The film had been shot using a toned down version of the script, which avoided the need for an X classification. However, not all the changes advised by the BBFC for an A classification had been made and the company was informed the film as it stood was likely to be classified AA uncut. There then followed further discussions between the BBFC and the company regarding what additional changes would be required for an A classification.

When the film was submitted for formal classification in early 1975 the finished version still contained material the BBFC was unable to accept at A. The BBFC wrote to the distributor stating that further cuts would be required to achieve an A rating. These included reductions to bloody violence, repeated use of the term 'Jesus Christ', use of 'sh**' and sex references. There was some disagreement with the distributor over reductions to language. The distributor wanted 11 year olds to be able to see the film, but the BBFC's Secretary, Stephen Murphy, reminded them that the A certificate would also permit children as young as 5 to see it. The distributor highlighted that the Monty Python TV programme was broadcast at 8.30pm but Murphy also countered the argument stating that this broadcast time actually indicated AA rated content, rather than milder A content.

The distributor agreed to reduce shots of blood gushing from the Green Knight’s vizor; the shot of blood gushing from the Historian’s neck; and substitute two of the 'Jesus Christ’s' with alternative exclamations. They argued that the other language and scenes where the BBFC suggested reductions were important to the storyline and comic moments and should be retained. The BBFC agreed to look at the film again once this reduced list of cuts were made and agreed to classify the film A without the other suggested cuts being made.

Monty Python and The Holy Grail was subsequently classified 15 on video in 1988, at which time the 12 certificate was not yet in use. More recently, in 2015, the film was classified 12A uncut for 'moderate sex references, comic violence'.