Dan Stevens reveals how he transformed from a Downton gentleman to a Disney Beast

Yet, taking the title role in Disney classic Beauty and the Beast, opposite Emma Watson as Belle, was a no-brainer for the 34-year-old, who has three children aged between ten months and seven years with his wife of eight years, the South African jazz singer and teacher Susie Stevens. “My kids love the animated version, so I knew it very, very well. I’d already practised my Beast voice for a couple of years before the audition, so I felt well-primed.”

In fact, his children, he admits, informed not only his choice but also his preparation for this particular role – that of an arrogant, selfish prince who is turned into a beast by an enchantress whom he has refused to help.

“I was going home in the evening after filming and dealing with my son Aubrey being in the terrible twos, and there is a lot of that that feeds into the performance,” he laughs. “There’s a stroppy, spoilt quality to the Beast – not that my son is spoilt; I don’t think he is,” he hastens to add. “Everyone goes through the terrible twos. And now there’s the “threenager” – which is a term I was recently introduced to – and as parents we say, ‘That is not how we behave!’ and hopefully by the time they are four, five, six years old, it’s over.

“But I wondered, what if someone was indulged and pandered to at that age and it carried on their whole life? Fitting that paradigm into a family film struck me as quite funny.”

Stevens himself certainly did not grow up in an abbey or a castle. He was adopted at birth in Croydon by teacher parents, growing up in Wales before winning a scholarship to become a boarder at Tonbridge School in Kent. From the age of 15, he spent summers performing with the National Youth Theatre, and, at 22, soon after graduating from Cambridge, was cast by Peter Hall in a touring production of Shakespeare’s As You Like It.

Aside from starring in The Line of Beauty for the BBC, he was primarily a theatre actor until he was cast in Julian Fellowes’s period piece.

The Line of Beauty

When he left the show after three seasons, in a dramatic Christmas Day car crash, he decamped to New York in early 2012 to appear in a Broadway play, The Heiress, with Jessica Chastain. And then, as tends to happen to many British transplants to the city, he never left. “I had always wanted to live here anyway,” he says when we meet at a hotel in Manhattan. “And I just thought, ‘I am making a big break anyway, why not change city?’”

The family has settled in Brooklyn Heights. “I am in love with my neighbourhood. Hart Crane, who is a poet I am mad about, lived here and wrote this epic poem about Brooklyn Bridge,” he enthuses. His notable neighbours these days include Lena Dunham, Adam Driver, Paul Giamatti and Matthew Rhys.

There are aspects of the UK he misses. “Indian food,” he nods, sadly. “And I find it hard to follow cricket and Arsenal properly over here because of the time difference. Getting up at 7am on a weekend to watch Arsène Wenger have an altercation with a referee takes its toll!”

Playing the role of the Beast was also particularly taxing. His transformation involved him wearing steel-capped stilts to give him the height and a hot, heavy muscle vest to give him the necessary heft.

“It was a pretty athletic job for me,” he nods. “I was physically conditioning my legs to be on stilts for 12 hours a day and also conditioning the rest of me so that I didn’t waste away – I was losing so much fluid from sweating.

“Underneath the muscle vest, I wore a special cooling vest, similar to what Formula One drivers wear, with refrigerator-style tubing. I would overheat, especially when we were dancing, so between takes there was a little tube that could be plugged in to ice-cold water to cool me down.

“I was honestly eating four roast dinners every day, just to keep any form of physicality,” he laughs. It seems you can take the Brit out of the UK, but you can’t deny him his roast… or four.

While the new live-action film stays true to the beloved 1991 animated version, there have been tweaks to both the Beast and Belle’s characters. “In our film, it’s not so much that Belle is teaching the beast to read – he’s not illiterate – but that she is reconnecting him to the better part of his nature,” says Stevens. “He has this beautiful library, which he doesn’t really appreciate, and he used to love to dance – she reminds him of all that.”

The notions of fear and outsider status that are examined in Beauty and the Beast also run through Stevens’s latest small-screen project, Legion, currently showing on Fox, in which he plays a young man suffering from an unspecified but violent mental illness.

“We can look at difference and embrace it and say, ‘How wonderful. How can we use this difference for our betterment?’ Or we can be afraid of it, demonise it, and try to stab it with a fork before running a mile.”

When we meet, he has just returned home after a couple of months in Ireland filming The Man Who Invented Christmas, playing Charles Dickens. He’s not, then, opposed to taking on more period pieces? “I am not saying that I am absolutely, resolutely never doing period drama again, but I wouldn’t necessarily do it in the same way,” he says, carefully.

“A lot of the things I’ve learnt in America, such as working in comedy a bit more, mean I’m able to be a bit more playful and irreverent now,” he says. “The next thing I’m doing is a period thing, too, albeit a dark one.” This month, in Wales, he’s filming The Apostle, a revenge thriller. “I feel that I’ve learnt an awful lot in the last five years – things that I could never have learnt by exclusively working in England."

Stevens might have tried his best, with wide-ranging roles and even a transatlantic move, to distance himself from being seen as the quintessential English gent. But for one who’s so charming, funny and frightfully well-spoken, it may take a while longer before the ghost of cousin Matthew is finally put to rest.

Beauty and the Beast is in UK cinemas now