Media playback is unsupported on your device Media caption Armando Iannucci and Dev Patel at the Toronto screening of David Copperfield

A new adaptation of David Copperfield is the latest project to take a colour-blind approach to casting.

Dev Patel plays the titular character in The Personal History of David Copperfield, which is directed by Armando Iannucci.

Speaking to BBC News at the film's Toronto premiere, Iannucci said the casting process felt "very natural."

"When I wanted to make David Copperfield, I instantly thought of Dev," he explained.

Image copyright TIFF Image caption Dev Patel has previously starred in Lion and Slumdog Millionaire

"Because he has those qualities of naivety, awkwardness, and yet strength at the same time. And he instantly was, for me, David. And he said yes, thankfully, because I couldn't think of anyone else, I didn't have a plan B.

"And I also wanted it to feel contemporary, although it's set in 1840. For the characters in it, it's the present day, so it should feel like the present day, and feel reflective of now. I didn't want to feel bound by how you make a costume drama."

Actors who have previously played the role have been generally white - such as Harry Potter actor Daniel Radcliffe, who made his acting debut as the young Copperfield in a 1999 adaptation on the BBC.

The new adaptation also stars Peter Capaldi, Rosalind Eleazar, Tilda Swinton, Nikki Amuka-Bird and Benedict Wong alongside Patel.

Image copyright Getty Images Image caption Armando Iannucci is well known for political satires like Veep and The Thick of It

The Personal History of David Copperfield's debut at the Toronto Film Festival was highly anticipated by film fans, as few details about the movie had emerged in advance.

An official trailer for the movie has still not been released, but the absence of any public reaction hasn't stopped it being snapped up by Fox Searchlight for distribution.

The film is due to play at the London Film Festival next month before its 2020 release.

Patel said: "I think [Iannucci's] choice to just cast the right faces for the part opened this movie up in such a way where you won't have people meeting him for the first time, and asking 'Who's David Copperfield, is he the magician?' - which is what I did.

"You'll have young children in schools looking at this movie and finding a face they can relate to, I hope," added the actor, who was Oscar-nominated for 2016's Lion and starred in 2008's Slumdog Millionaire, which won eight Oscars.

"For me, I just think back to my younger self and what he would think about older Dev being able to be part of this movie with this cast, and I feel so lucky, and I want that opportunity to extend to my peers as well, because this is why we do it. We don't do storytelling and exploring to be put in boxes, we do it to be free and live dreams so we can put them on screen."

Image copyright Getty Images Image caption Laurie praised the way Dickens tackled mental illness in the novel

Like practically all awards season films, the new Copperfield is long - around two hours - but in this case that's largely justified by the vast scope of the original Charles Dickens novel.

"If there's too much plot in the film to jam into this synopsis, be assured there's too much plot in the novel to fit in the film," wrote John DeFoe in The Hollywood Reporter.

He also praised the director's pacing of the film, commenting: "Iannucci has shown more visual invention than in his earlier work, with dazzling little transitions that help us not to be too grumpy about how little time we spend in some sequences.

"[The film] turns the author's well-loved autobiographical epic into a fast-moving yarn, sometimes hilarious and always entertaining."

It's been two years since Iannucci was last in Toronto, launching The Death of Stalin, which starred Steve Buscemi and Jason Isaacs.

The writer and director is best known for his biting political satire, particularly in his creation of TV series Veep and The Thick of It.

Copperfield, therefore, marks a slight change in tone for the director. It's a softer and more human character study, with significantly less swearing than is usual for an Iannucci project.

"I've never really thought of myself as someone who specialises in swearing," he laughs, "it just so happens that [those shows] conveyed worlds in which people do an awful lot of swearing.

Image copyright Getty Images Image caption Dev Patel said Iannucci's casting "opened the movie up"

"However, what I did want to make sure was we didn't shy away from quite tough moments. The physical abuse of a child, the working conditions, the homelessness. I didn't want to shy away from that, but I also wanted this to be a film that any generation could come and see."

The Personal History of David Copperfield also stars Gwendoline Christie, Ben Whishaw and Hugh Laurie, who points out his character Mr Dick was one of the earliest explorations of mental health in literature.

"He's an unusual character in that it's one of the first efforts that I know of in novel form to deal with a character who suffers from mental illness, who has been traumatised and has become in some cases delusional and actually psychotic," Laurie told BBC News.

"And to see not exactly healing of that problem but to see the joy in him, which he's still capable of, to see that develop through his relationship with David Copperfield is a beautiful thing.

"Remember this was a time when the mentally ill were very often consigned to institutions, where there was no real prospect of a way out, of any sort of care. That was just the sort of understanding we didn't have of mental illness."

Speaking about the themes of the novel more widely, he said; "I hope that it's fresh and relevant after all these years because the basic constituents are eternal. It's love and it's home and it's finding your place in the world, it's loss, and grief, and all those things that just don't go away."