Rupert Everett is in final talks to play King Charles I, the despotic British monarch who ill-fatedly believed in the "divine right of kings", in Mike Barker's English Civil War story Cromwell And Fairfax.

Everett joins Tim Roth and Dougray Scott in the $23m IAC Films project that is thought to be the first time this tumultuous period in British history has served as the backdrop for a feature film since Ken Hughes' Cromwell in 1970, which starred Richard Harris as Oliver Cromwell and Alec Guinness as Charles.

Shooting is to start in the UK next month, with Roth playing Cromwell, the iron-willed military genius who successfully led the forces of parliament during the English Civil War that broke out in 1642. Scott plays Thomas Fairfax, the general of the English armies, whose victories at Marston Moor in 1644 and Naseby the following year brought the war to an end.

Although Jennie Mayhew's script focuses primarily on the relationship in the aftermath of the war between Cromwell and Fairfax (who played only a minor part in the Hughes' film, where he was portrayed by Douglas Wilmer), the film will also cover Charles' trial for treason and his execution by beheading.

Barker's new film shows how Cromwell and Fairfax, previously such good friends during their battles with the royalist forces, were then driven apart by their political differences as they tried to decide how best to build a new English state in place of the defeated monarchy. Cromwell, who was one of the signers of the king's death warrant, eventually ruled England from 1649-1658 under the title of Lord Protector.

"We wanted a strong adversary and we are delighted with [Rupert Everett], who is perfect casting," said Kevin Loader, who is producing for Natural Nylon. "There aren't that many British stars. They were also all three of the same generation, so that's great."

IAC, which is handling international sales, is in final talks with UK performers union Equity on an emergency deal to shoot despite the current actors strike. The title is one of eight European films in a slate deal between IAC and LA- and Brussels-based production and financing Corsan.