A film based on the hit TV series Horrible Histories is now in production.

Rumours of the movie's development first circulated late last year, and British Comedy Guide can now confirm that filming is under way.

Based on the huge success of the CBBC sketch show, itself based on Terry Deary's popular factual childrens' books of the same name, the film tells a single narrative story, with songs in Horrible Histories' now trademark style.

Casting has yet to be confirmed, but a range of guest stars from across the British comedy spectrum are expected to appear.

The screenplay for the film has been written by acclaimed writer and director Jessica Swale, best known for her Olivier Award-winning stage comedy Nell Gwynn, which is also in development for a film adaptation.

BCG understands that the Horrible Histories film follows a pair of teenagers and tells the story of Queen Boudica, who lead her Iceni tribe to a bloody revolt against Roman occupation of Britain in the middle of the first century AD, in the year 60 or 61.

It is being produced by Citrus Films and Altitude Film Entertainment.

Boudica has previously featured in the TV sketch show a number of times, most recently being the focus of a Series 6 episode, in which she was portrayed by guest star Lorna Watson (pictured, above).

Directed by the sketch show's co-director Dominic Brigstocke, the movie is being produced by the series' original producer, Caroline Norris. The original cast - including the likes of Martha Howe-Douglas and Mat Baynton - are currently in production on their new BBC sitcom Ghosts and not believed to be involved.

A release date for the film has not yet been set, but it is likely to open in cinemas during the second half of 2019. More details are expected to be released next week.

Meanwhile, filming for an eighth series of the hit CBBC sketch show is also under way. The series is expected to be broadcast in mid-2019.