t is high summer and, while Lesley Manville may be suffering a bit with hay fever and the heat ("I'm so white, all I do is burn"), she doesn't do wilting. Soon to head outside to tend to the ailing garden of her London home, she is enjoying a rare period of rest after six almost unbroken months of Oedipus on Broadway and then Les Liaisons Dangereuses at the National. She keeps, incidentally, the Tony she won for playing Jocasta in Oedipus on a shelf by the computer, "next to its friend, Larry Olivier" – an Olivier awarded for the same role.

"You don't go into a job thinking about awards," she says, before grinning conspiratorially. "Listen, you don't say to an Olympian, 'Oh, is it OK that you didn't win?' Yes, you like to win!"

Manville has done a fair bit of winning recently, and not before time. The last 15 years have seen her graduate from widely respected actor to garlanded star: since 2011 there has been that Tony, two Oliviers, an Oscar nomination for Paul Thomas Anderson's Phantom Thread, Emmy and Golden Globe nominations and seven Bafta nominations. Her cinematic collaborators have included not only PTA but Luca Guadagnino, Alfonso Cuarón and Joel Coen. This relatively late blooming has come as a relief.

"I'm so glad I was never flavour of the month," she says, "because it's so hard to maintain. No one went to LA for pilot season when I was young – we were just interested in doing the work. But you're right, there has been a shift. Winning the Olivier for Ibsen's Ghosts in 2014 took me somewhere else, theatre-wise. An Oscar nomination makes a difference. A whole sequence of high-profile television, not least The Crown, which obviously wasn't all about Princess Margaret but boy did Peter Morgan write me two astonishing episodes. Mrs Harris Goes to Paris brought me to a new audience, and Mum is the thing I still get stopped about most."

These are just some of the most recent projects from an amazing body of work, one of which Manville – whose combination of wry wit, warm intelligence and stern savvy keeps me on my toes throughout our conversation – is rightly proud. Marble Hall Murders, her new TV series, starting on BBC One this week, completes Anthony Horowitz's trilogy of ingenious Susan Ryeland mysteries. It may be one of her lighter pieces, but it's no less satisfying for that.

Manville was willingly cajoled into returning as publisher-cum-crimebuster Ryeland by Horowitz, who offered to write a third book if she'd do a third series. Susan is back being single, back in London and back in publishing – albeit reluctantly – when a young writer proposes to conclude the bestselling saga of fictional detective Atticus Pünd. As before, many of the cast take dual roles as fact and fiction intertwine, and Pünd's investigation into the murder of a publicly beloved, privately monstrous children's author in Corfu is reflected by events in Susan's world, where her sparring partners include Mark Bonnar and Rupert Penry Jones. If it is indeed the end, Manville will miss Susan immensely.

"She feels closer to me than a lot of other parts I've played. I like to think I don't conform to a received notion of how one should be when one reaches a certain age. I love the fact that she wears these fabulous clothes, drives an open-top red sports car – I used to drive an MG in my 20s, although it broke down all the time – and doesn't put up with any shit. Like her, I'm very clear about who I am. I've found myself at this point in my life. And although I'm absolutely terrible at guessing whodunnit, I've caught out a few boyfriends in the past, so my detective work hasn't been all bad."

Manville, now 70, grew up on a council estate in Hove, a seaside town in East Sussex, one of three daughters of lifelong Labour supporters. "Those principles stay with you. My early influences were very leftwing, working at the Royal Court with actors and playwrights who felt the same way." These included Andrea Dunbar and Caryl Churchill. "I really want the Labour party to be everything it could be, and under Andy Burnham, we might have a glimmer of hope that happens. I've got a lot of time for him."

Manville was a gifted performer from a young age, albeit not in the art form she would go on to conquer. "I had a really good, classically trained voice when I was young," she says. "I could have been an opera singer, but something about it felt formal and stiff, so my 15-year-old brain went, 'OK, I'll go and do musicals.'"

Thanks to a council grant she commuted daily to London's Italia Conti stage school, and, after O-levels, studied dance, singing and drama. "From my first job in a musical when I was 16 until I was 22, I did every job I was offered. I was a presenter. I did two pantomimes, a musical, a telly play, everything, but I never thought about playing characters. I just played me. Meeting Mike Leigh was the lightbulb moment, not just because he told me I was good but because I played someone a million miles from me. And I thought, 'This is what I want to do.'"

That was in 1979, and Manville has now worked with Leigh more than any other actor, their eight films together producing what were, for years, her defining screen roles. Lonely daytime drinker Mary in Another Year, and the nervy, vulnerable breadwinner Penny in All or Nothing, in particular, condensed so much of what makes her great: the precision of characterisation, the deep dredging of despair, the dogged resilience. She still values Leigh's opinion more than almost anyone else's.

She even turned down an offer to join Arlene Phillips' dancing troupe Hot Gossip. When I suggest she could resurrect her dancing on Strictly, she gently corrects me, explaining that she never really let it die. I should have guessed from her enviably upright deportment. "I've spent every night of the last three months dancing with professionals in Les Liaisons Dangereuses," she says. "It felt like an extreme sport and it's been wonderful!"

She pauses before taking a brief, impassioned detour. "Thank God, just because we're over 50, we don't have to have walking sticks – or not be thought of as sexual any more. We are! Oedipus and Les Liaisons were both highly sexualised pieces of theatre and I love that. Anyway, if I'd been asked to do Strictly 15 years ago, I might have said yes. Now, I'm not available much."

She has been busy ever since her breakthrough TV role back in 1975, in ITV's then new daytime soap Emmerdale Farm. "My first screen kiss was in a cowshed!" she says, hooting with laughter. "My character was younger and adored an older man. It was more affectionate than passionate. I've been kissed in more glamorous locations since."

As with so many actors, soap opera gave her an "amazing grounding" in the technique and discipline of screen acting. "But I knew it was time to go. I remember a lot of the cast saying, 'Oh, you shouldn't leave. It's great money. You've got security.' I just thought, 'I know, I hear you, I've learned a lot, it's been amazing. But I'm off.'"

At times, her work rate frankly boggles the mind. For 10 weeks in 2018, for instance, she spent her days filming the costume drama Harlots in Watford and her evenings on the West End stage for Long Day's Journey into Night. Where did this all come from?

"I just want to keep going. You're either that person or you're not. I'm very good at looking after myself. Just crack on with it is very much my philosophy and not a lot fazes me. If there was an Olympic event for multitasking, I'd win! When I was a single mum, I went back to work because I had to." Gary Oldman, her first husband, left her, and the UK, three months after their son Alfie was born in 1989. "When I had too much to do, a play to learn and a baby who needed feeding and bathing and stories, I allocated my time much better."

Alfie is now a father of three and a cameraman who has worked on projects with both his parents. "My friend Alan Rickman was on Harry Potter," Manville remembers, "and he said, 'Alfie, I'll get you through the door [as a runner], but the rest is up to you,' which was exactly right. Now if I see Alfie at work I'll think, 'What are you doing here?' What a privilege. And he likes me. I like him. So it's a win-win."

Manville's work ethic and eye for quality endure: days after we speak, it is announced that she will star with Anna Maxwell Martin in a new production of the American tragicomedy August: Osage County, and she is currently filming a new Prime series called Escorted, playing a Manhattan nightclub singer opposite Brett Goldstein as her son. There will be no slowing down for this formidable performer.

"I've got as much energy as all of those dancers I've just finished working with," she says matter-of-factly. "I really am a bit like Susan Ryeland. I couldn't give a fuck how old I am!"