It’s late afternoon, and actress Allison Janney is perched on a hotel sofa in London’s Knightsbridge, big wide smile and looking very glam in a mauve velvet dress and heels. Right now, her mind’s spinning. “What’s the expression?” she says, chiding herself as she tries to remember the phrase “truth is stranger than fiction”. An exasperated look crosses her face. “My jet-lagged mind is not accessing anything!”

The transatlantic tiredness is only going to get worse. When we meet, in mid-December, Janney has just been announced as a Golden Globe nominee for her latest role – as the vile mother in ice skating drama I, Tonya. By January, she’ll have won the Globe and the Screen Actors Guild award. She won a Bafta last week for Best Actress in a Supporting Role and in early March she has her eyes repeating that at the Oscars.

While Janney is no stranger to awards – she’s won six Primetime Emmys, four for her role as White House press secretary C.J. Cregg, in The West Wing – she’s never been nominated for an Oscar. She’s the red-hot favourite and anything but a flat-out win will be a shock. It means a whirlwind of lunches, chat-shows and press engagements, the spotlight well and truly on her.

Alison Rowat's film review: I, Tonya (15)

Excited she may be, but Janney, 58, is not one to let it all go to her head. “Fortunately, I think I’ve been around long enough that people respect my work and know I’m a good actress,” she says. She’s more touched that her role in I, Tonya was written by her friend Steven Rogers, who refused to sell the script unless Janney got the part. “My friendship with Steven and his belief in me is what makes this even more special.”

Remarkably, after a career that stretches back to 1989, when she made her debut in a little-remembered Sandra Bullock comedy Who Shot Patakango?, it took just eight days work on I, Tonya to garner all this attention. Playing LaVona Fay Golden, mother to real-life Olympic ice-skater Tonya Harding, it was more than enough. “I’m glad I didn’t have to live with LaVona for much longer. She was a hard woman to carry around.”

You can say that again. LaVona is one of the nastiest mothers ever to be committed to celluloid. “She’s up there with Mommie Dearest, for sure!” jokes Janney, referring to the 1981 movie where Faye Dunaway played actress Joan Crawford, who allegedly traumatised her adopted daughter, Christine. Quite simply, LaVona is cold-hearted and cruel, pushing Tonya (played as an adult by Margot Robbie) to the limits when it came to practising skating.

The story revolves around the scandal that broke in 1994, when Harding’s husband was accused of orchestrating on a physical attack on Harding’s rival skater Nancy Kerrigan. Janney remembers the incident all too clearly. “It was the advent of the 24 hour news cycle. She pre-dated O.J. [Simpson] and the Menéndez brothers. All that. She was the first story to hit that 24 hour news cycle and it was a narrative that people couldn’t get enough of.”

Funny, tragic, bitter, twisted, I, Tonya is really a film about truth, or versions of it, as various characters – including LaVona – speak to camera in trying to get their side of the story out there. “In the tapes that I watched, you can see she’s someone in denial; it hurts her, the fact she’s been vilified by her daughter. She pretends it doesn’t, that she doesn’t care, that it doesn’t hurt her. But I can see through her in the interview that it does.”

Intriguingly, Janney related to Tonya Harding’s story, not least because she had her own ice skating ambitions when she was young. Her father Jervis, who worked in real estate, owned a building with an ice skating rink. “I had access to free ice 24/7. And I took advantage of it. I became passionate about wanting to be a figure skater.” In her early teens, the young Janney would get up at 5am to practice.

Growing up in Dayton, Ohio, Janney’s parents were quite happy with her sporting ambitions. “My father loved it. My father’s in his 80s, plays tennis every day and is always supportive of any activity like that for us, especially physical stuff. He bought me a bicycle and marked out my route to get the ice skating rink every day. I think he was really thrilled that I was doing something like that.”

Alison Rowat's film review: I, Tonya (15)

Janney can still remember her first skating programme. “My coach picked the music to Man of La Mancha and the music scared me so much! I think it scared me out of wanting to be a skater! You know that music? – dan-dan-dan-da-da-dan. It’s just a very powerful piece and he picked it for me because I’m a tall drink of water and commanding and powerful, but it didn’t suit my insides very much. It terrified me.”

At this point, I’m hoping Janney will burst out into a chorus from the aforementioned 1964 Don Quixote-inspired musical, with its lyrics “My destiny calls and I go”. She doesn’t, but Janney has sung her heart out in the past on Broadway. She starred in the 2009 version of the classic workplace comedy 9-5, playing AS Violet Newstead, the office supervisor made famous by Lily Tomlin in the movie.

Acting came about after her ice-skating career was cut short following an accident at a party – when she fell through a plate-glass window. Attending Kenyon College in Ohio, Janney was even directed in a play there by Paul Newman (a former pupil) and encouraged to keep on acting by the legendary star and his wife, Joanne Woodward. Training at the Neighborhood Playhouse in New York, where she first met I, Tonya’s scriptwriter Steven Rogers, she gradually started getting roles.

In 1994, she co-starred with Stanley Tucci on stage in the Nicky Silver play Fat Men in Skirts; a couple of years later Tucci cast her in his restaurant-set comedy Big Night. “That was a big film for me to be a part of. It was a small film but it had a big impact. I think of that as being a really breakthrough for me.” Two years on, in 1998, she starred in Mike Nichols’ political drams, Primary Colors, which led to her casting in The West Wing.

As much as she loved the Aaron Sorkin-created show and the steady pay-cheque, it was a gruelling schedule: twelve-to-eighteen hour days for ten months of the year. “In the first couple of years, we had maybe five weeks off,” she says. “It was a big sacrifice. They call those hour-long drama shows in United States the golden handcuffs. It’s a wonderful job to have and you’re lucky to get it and you get paid well, but you don’t have a life.”

It may be why Janney has never married. When we met several years ago, for the beloved teen pregnancy movie Juno, she told me she hadn’t found the right man yet. “I’d love to find my life partner. I’d love to find him. I don’t know how I’m going to do that. But that would be great. That’s a big goal in life. To find someone who really gets me, who really understands me, and we can share a life together. It doesn’t have to be marriage. But it would be really nice to find that person.”

What about now? She shrugs. “I have a lot of great men in my life right now – like Steven [Rogers], my good friend. And I’ve got my dogs [she has three Australian Cattle dogs at her home in California].” In many ways, her life is sorted without need for a partner. Aside from the crazy awards season she’s currently embroiled in, she has a regular gig on Mom, a TV sitcom in which she plays a former cocaine addict.

“It deals with the world of recovery, and people in recovery from addictions, alcoholism, drug addicts,” says Janney, whose own brother Hal tragically took his own life following years battling substance addiction. “I love what Mom does for people in recovery; it takes the stigma off that and shows people living in recovery and having good lives, productive and laughter and joy. There’s a way to do it to get through it.”

As for the recent scandals that have been rocking Hollywood and the emerging #MeToo and #Time’sUp movements that have seen women recount their stories of abuse in the industry, Janney admits surprise at the speed of the developments. “When we made this movie, none of this had happened. It’s a whole culture shift that’s really important and really devastating. The potential for growth and change – and important change in Hollywood and the world – is great right now.”

Alison Rowat's film review: I, Tonya (15)

Her I, Tonya co-star Margot Robbie has been particularly vocal as part of the #Time’sUp movement. And there is no doubt that Janney’s night at the Oscars will be remembered as much for talk about curbing abuses of power as it will for the winners and losers. “If I had a daughter I’d be thrilled right now to think about her growing up in a world that [has this],” says Janney. “It’s as if we’re in the middle of an Earthquake.”

I, Tonya opens on February 23rd.