90% of the crowd during the sequence at St. Peter's Field were digitally duplicated and created; in reality, there was 200 extras. The sequence was filmed at Tilbury Port, and many of the buildings were also added in post-production, re-created from historical records.
The speech delivered by Rory Kinnear in "London", was filmed in Gainsborough Old Hall, Lincolnshire, and was written by Kinnear himself
The film was selected to be screened in the main competition section of the 75th Venice International Film Festival. The film received its UK premiere on 17 October 2018, as part of the BFI London Film Festival, in Manchester. The screening marks the first time the festival has held a premiere outside London. Leigh said he was delighted that Peterloo would be premiered "where it happened."
The film Peterloo will mark the 200th anniversary of the notorious Peterloo Massacre.
Production used the Tarred Yarn Store and the exterior of the Ropery to double as a Cotton Mill in Manchester at the Chatham Historic Dockyard in Kent. St Mary's Marshes on the Isle of Grain also appears in a short scene at the beginning of the film, when a lonely figure is seen walking along the marshes.
Tim McInnerny is the second 'Blackadder' actor to take on the role of the Prince Regent. The first being Hugh Laurie in Black Adder the Third (1987).