Frances de la Tour on ITV drama Professor T, the future of the theatre industry and voicing the Queen

"She's a wonderful character, because... well, she's monstrous, really!" she tells RadioTimes.com over the phone. "Which also makes her very funny.

"But it's dark. I think fundamentally, it's because it was originally a Belgian series," she continues. "And I love those what we call Scandi noirs or, you know, the Walter Presents dramas. He gives us all these incredibly dark but interesting series and characters.

"And the character of Professor T himself is astonishingly complex, so the mother and the son is a powerful relationship. I mean, they're very dependent on each other and love each other, and fight each other. So the part did offer a lot of avenues to explore and to enjoy."

Of course, a detective series with a flawed central character is no new thing – and indeed Miller has compared his character to both Sherlock Holmes and Dexter – but de la Tour reckons that there is enough fresh appeal to Professor T to make it stand out from the crowd.

"I think in a way, you have to have that flaw somewhere in the character," she says. "And there have been many, like Cracker and all sorts of really great TV things, where there are main characters that have problems, whether it is alcohol or terrible relationship with their wives or something like that.

"But this is unusual, because he's got OCD and that can be very funny but it's also tough," she continues. "And I think you see both sides, you see that it's incredibly tough for him to think like ordinary people, for want of a better word. But also, you know, it gives scope to be very different."

Naturally, the role required working very closely with Miller, but she said that the mother/son dynamic was easy to get a handle on, in part because the former Death in Paradise star was so "wonderful" to work with.

"He was a real leader," she says. "But he never sort of threw his weight around or anything like that, he was just very caring about the whole thing. And he's very quiet. He said, let's just go to another room and rehearse this for a few minutes, which we did with the director, and found all sorts of lovely layers.

"And once you've done the first scene, and you've explored it then it seeds the next scene. And you just have to tell yourself, this is not what we do in theatre. In theatre you have four/five weeks of rehearsal so you can start from a blank page and very slowly start colouring in. But in television or film, you have to guide it. And really, they're almost two separate crafts."

If there's anyone who knows about working in both of those crafts then it's de la Tour. Throughout an extensive stage career, she's won three Olivier Awards and a Tony, and she says that, while finding the balance between the two forms is very important to her, it's theatre that has provided her with the basis for her career.

"I've spent my life in the theatre, mainly," she says. "I know all actors get known for a successful television thing, but that's not our lives. I'm old now, I mean, I've spent 55 years doing it, and I would say 45 of those years were on stage.

"And without theatre, I wouldn't have been able to do the television," she continues. "They often say if you want longevity in this business, be a theatre actor. Because there is a point where producers look for what they call gravitas, which is an actor that has been at it a long time. And yes, you can spend your whole life on screen there's no question about it. But personally, I don't know anything different other than thinking about what it would be like on stage."

While the film and TV industry has certainly had to take some hits in the last year, it's nothing compared to what the theatre business has had to deal with – and indeed de la Tour herself admits that at times it's felt like the industry was "dying on its feet".

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But with restrictions seemingly coming to an end, does she feel optimistic that the theatres around the country will make a full recovery? "It's all about money isn't it," she says. "There will be private money put into commercial theatre, because that's how they work. And I'm sure a lot of people with a lot of money will continue to do that.

"But my worry was subsidised theatre. Because all reps are subsidised, The National Theatre is subsidised, the RSC is subsidised. I was worried about what we call the fringe theatres – you know all the small, many, many theatres like The Southwark Playhouse and The Trafalgar and The Almeida, all those who are desperate for funding.

"And most of us now have local theatres. I live quite near Finsbury Park and there's the Park Theatre which does some wonderful stuff. And you just think' Oh, please don't let that die', because that is where actors like Ben and myself, that's where we all learnt our craft.

"So I hope so, but I do think they need a bit more support. I think the government... you know it's difficult to get governments to really understand the urgency and the needs that people have for entertainment of all kinds."

For her part, de la Tour has done her bit to help keep the industry afloat; earlier this year she participated in a project called Still Life for the Nottingham Playhouse, which was billed as "a piece of digital theatre telling the tales of the city we love." The project consisted of a series of Zoom monologues shot at various locations around Nottingham – several of them written and performed by emerging talent – with all the proceeds going directly to the theatre. De la Tour performed a brand new piece that had been penned specially by Alan Bennet for the series, and she described it as a "lovely experience."

"I mean, it's a slight contradiction in terms because you're not watching it live," she says. "But I was thrilled. I mean, it was the first bit of acting I did since COVID began, and of course, I knew Alan's work very well. And Adam [Penford, director] and his cameraman and soundman came to my house and we moved the furniture around and we filmed it. And then I saw it and I thought, 'Oh this does look like a proper little film,' even though it was incredibly short."

On the whole, though, de la Tour doesn't think it should just be left to those who work in the industry to keep it going – and she reckons that a lot more could be done not just by the government but also by some of the huge companies that have profited from the pandemic.

"I do think more can be done by people with a lot of money who became very rich through COVID – you know, the big people like Apple and Google and Amazon – and all those because they are so rich," she says. "There's an awful lot of money that could be spent by very rich, not just billionaires but trillionaires. But instead, they go to the moon. What can you do?"

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Next up for de la Tour is a different role entirely – she'll be voicing a version of the Queen in Gary Janetti's animated satire The Prince. She previously worked with the American writer on the aforementioned Vicious, and she says it was a joy to reunite with him.

"That was hysterical," she says. "The actual animation is hysterical and also what Gary's written, and it's brutal about the Royal Family. What can I say? I better not say anymore, I don't think, or we'll be heading for the tower!"

Professor T airs on Sundays at 9pm on ITV. Looking for something else to watch? Check out our TV Guide or visit our dedicated Drama hub.