The Personal Life of David Copperfield, Armando Iannucci's adaptation of Charles Dickens's famous novel, will open this year's London Film Festival.
Slumdog Millionaire's Dev Patel plays the lead role, which has traditionally been portrayed by white actors.
Director and co-writer Iannucci said it felt important to ignore ethnicity, and to simply cast the best performers.
"You shouldn't have to bat an eyelid, and you don't. Because the best people are cast for the parts."
"I've noticed it's something that's been happening in theatre for a long time," he told the BBC.
"Dev has the potential to flit in seconds from being vulnerable, and gawky and funny, to being quite dramatic and strong."
Avengers star Benedict Wong, Nikki Amuka-Bird and "just out of drama school" Rosalind Eleazar will also feature.
Eleazar takes the role of Copperfield's wife, Agnes.
The cast also includes Peter Capaldi, with whom Iannucci worked with on The Thick Of It and In The Loop, and Tilda Swinton.
The film may be a full-on period costume drama, but Iannucci's one golden rule was "no Dames and no cobbles".
He wanted the film to "feel very much of now, really" and to reflect society in everything from casting to the issues it highlights.
"I've tried to give it a contemporary feel," he says. "The issues in it are all very relevant. It deals with poverty, and neglect, and homelessness, and riches, and status anxiety and relationships.
Film studio fire
"It's a story for every time and every one," he adds.
Many previous Dickens adaptations haven't necessarily reflected the vibrancy and diversity of London. In his film, Iannucci wants the capital to be seen as exciting and full of potential.
"People flocked to London. It's frightening, it's huge, it's iron and steel and machinery and feels modern. You know, it's a place people can get lost in. It's a place people come to because they want to achieve something."
Iannucci spoke to the BBC from Leavesden Studios, just outside London, less than a week after a fire there badly damaged one of the sets for his next project, the HBO space comedy Avenue 5, starring Hugh Laurie.
"It was a huge set and we shot an awful lot of the series in it," he says.
"We've managed to work out how we get to the end of the season without that set. And I just feel for the people who've spent the last 18 months designing it and building it and constructing it and putting it together, really.
"We're going to get the final two [episodes] shot in the next couple of weeks. And season one will be done!"
As for The Personal Life of David Copperfield, Iannucci says being given the London Film Festival's most prestigious slot is "very exciting and a great stamp of approval for the film".
The film has its European premiere on the opening night of the 63rd London Film Festival, which runs from 2 to 13 October.