Rebecca Front and Tom Hollander trade comedy for drama in ITV's Doctor Thorne

Invite Hollander to comment and he is likely to say, “I refer you to my previous answer.” (And he does, twice).

Ask him if filming in the wonderful houses and gardens that serve as a backdrop for the ITV drama has left him with a liking for the lifestyle of the British aristocracy. And the answer is “No.”

Ask if he’s looking forward to seeing more costume drama on television. It’s, “What makes you think there is going to be more of it?”

Does he think the costume drama has a particular appeal to the British?

"Well," he says, "You don't watch The Exorcist at nine o'clock on Sunday evening, do you?" Hollander then withdraws into the recesses of his high-backed chair, where he will spend much of our interview.

Happily, Front is not backward at coming forward. “If I never have to wear another corset again,” she volunteers, “I will be very glad.” Front has been wearing a lot of corsets recently, squeezing into restrictive underwear on behalf of both Leo Tolstoy and Antony Trollope.

She was hard-up noblewoman Anna Mikhailovna Drubetskaya in Andrew Davies’s adaptation of War and Peace and is now the similarly straitened Lady Arabella Gresham in Julian Fellowes’s adaptation of Anthony Trollope’s Doctor Thorne, n which Hollander plays the eponymous doctor, and Ian McShane also appears as stonemason turned railway baron Sir Roger Scatcherd.

Trollope’s dramatic portrayal of social class, financial scheming and doubtful parenthood, book three of the Chronicles of Barsetshire series, was published in 1858. That’s some 45 years after events in War and Peace but both productions depend heavily on the sculptured corsetry that male television executives of a certain age find so attractive. “Oh god, they were uncomfortable!” says Front, with some feeling. “When we were filming I’d look at myself in the mirror and think, ‘Ooh, you look pretty nifty’, but I bow to no one in my loathing for a corset.”

Front looks pretty nifty today. She’s had an expensive hair do and put on a sparkly top for our interview. Hollander is less sparkly, pairing suit jacket with jeans and trainers: he gets incrementally scruffier the further down he goes. But he does like putting on 19th-century clothes. “It’s the dressing-up box,” he says. “The childhood thrill of now I am going to pretend to be someone else. It’s like going on holiday from yourself.”

If going on holiday from yourself sounds a little downbeat, then Hollander is. The 48-year-old actor, known best for Rev, Pirates of the Caribbean and In the Loop, is not in a bright mood. When enthusing about a scene in episode one of Doctor Thorne, when he and Front clash over the romance between Lady Arabella’s son Frank and Doctor Thorne’s illegitimate niece Mary – a romance at the centre of the plot – he can’t or won’t remember it (“Which scene?”) until Front describes it for him.

“Ah, yes,” he then says. “You played your character, very brilliantly, as someone who is relatable, when you could have really played her as a snobby cow.” And he’s right. Front is spot on as a woman in, as she puts it, “an awful predicament” – desperate to hang on to an ancestral home that can only be saved by marrying her son into new money.

Hollander says he took his part because he likes Doctor Thorne’s personal qualities. “I don’t think I’ve played someone strong and really courageous before. A character who is as purely loving and as selfless.” Did any of that rub off on him? “One of the pleasures of acting,” he says rather sternly, “is to pretend to be other people. It’s rare that one’s own personal life is quite as dramatic as Hamlet’s.”

Does he think that the public likes him in nice roles? “Are you saying that the part is quite like Rev?” Hollander demands. “Is that what you are saying?” No. “Are you inclined to say that?”

It’s possible Hollander is accusing me of comparing Doctor Thorne to Rev. “I don’t think I’m typecast,” he says. “I do other roles. I am a villainous type in something called Taboo [an upcoming BBC1 revenge drama set in the early 19th century starring Tom Hardy – more dressing-up needed]. And in The Night Manager [which is scheduled opposite Doctor Thorne on BBC1], I play an evil, unpleasant arms dealer’s sidekick.”

Front’s character, Lady Arabella, is not villainous or evil, but she will do almost anything to save her family’s social position – including preventing the marriage of Frank and Mary. “She adores her son,” says Front. “Yet she’s happy to sacrifice his happiness. But Julian [Fellowes] told me she’s not a monster.”

Front had a six-week gap between shooting War and Peace and Doctor Thorne, leaving the arms of Andrew Davies for the embrace of Fellowes. “I couldn’t say which was preferable,” she says when I ask. “I do think that Julian is probably drawn to Trollope because it’s all about backbiting. What would be intriguing for me would be seeing them swapped over: Julian doing the Tolstoy, Andrew doing Trollope. But they were just so different.”

In fact Davies has successfully adapted Trollope in the past for the BBC, first with The Way We Live Now (2001) and then with He Knew He Was Right (2004). Fellowes arguably owes his screenwriting career to Trollope. It was on the strength of a film treatment he wrote of The Eustace Diamonds that he was brought to the attention of Hollywood director Robert Altman and his breakthrough hit, 2002’s Gosford Park, was made.

Like Gosford Park – and Fellowes’s subsequent Downton Abbey – Trollope’s novel finds much of its drama in the machinations of Britain’s class divide.

Though there is disagreement from the high-backed chair about that. “Are you saying if it wasn’t about class we wouldn’t be interested in it?” Hollander asks. “If you watch it, you might actually feel relief that society is not as stratified as that any more, that we all have so much more freedom.”

Do we? “Of course we do. The barriers most people were facing in that period just don’t exist now,” he says. “There are vestiges, but it’s nothing. Things are not as stratified and regimented as they were then.”

“When I went to drama school, RP [Received Pronunciation] was still referred to as Standard English,” says Front in agreement (in near-perfect RP). “But that’s crumbled away, everybody doesn’t have to speak the same way now, pretend to come from the same background or gone to the same kind of school.”

Hang on, what about the domination of the acting profession by public schoolboys like Eddie Redmayne, Benedict Cumberbatch and Damian Lewis? “It’s not impossible to be an actor if you went to state school,” says Front with feeling. “I went to state school. But there is a problem of affordability, I know one major drama school is worried that only rich kids can access an arts education.”

Hollander, educated at 759-year-old Abingdon public school, boarding fees presently £12,320 a term, scoffs at this. “Isn’t it just that three actors who seem to have gone to public school are getting highly visible work? Drama schools say if arts funding is cut people can’t afford to go, but I didn’t go to drama school.

"When I started in the profession there were very visible actors who were Scottish, Welsh or regional. Lots of working-class-hero leading actors – it was not fashionable to sound posh. Now I’m middle-aged it’s fashionable to sound posh if you are the generation behind me.”

Front doesn’t think much to being fashionable, either. “It’s a terrible mistake to go through your career, or indeed your life, worrying, ‘Do I fit into a groove, am I acceptable?’” she says. “You’ve only got what you are and the background you come from and as an actor you try and reinvent yourself according to what parts come in.”

Both actors seem to be riding a tide of success at the moment. “No actor thinks that,” says Hollander, “unless they are on really, really brilliant anti-depressants.” Front disagrees, as well. “And it isn’t a tide. Tides last a few hours. It’s actually a wave. It comes in and then goes out again immediately. When I walked off the stage with my Bafta for The Thick of It [in 2010] I thought the offers would come my way, and I got nothing for six months. I’ve had actors say you must feel it’d all plain sailing now. How could an actor think that was ever possible?”

“It’s not a stable profession,” Hollander says. “It can be very exciting but sometimes it’s also nerve-racking, scary.” Scary? “Not scary like being in the SAS.”

Front nods. “Yes, I’m glad you said that. Nothing comes across as more ‘wanky actor’ than saying it’s an incredibly risky profession,” she says. “There are people out there defusing bombs.” I know how they feel.

Doctor Thorne starts Sunday 6th March at 9pm on ITV