‘Mrs. Wilson’: Ruth Wilson plays her own grandmother in a twisty 'Masterpiece’ tale of love, bigamy, and government secrecy

Growing up, Ruth Wilson never quite knew where her drive to perform came from.

“I didn’t grow up in a family that encouraged acting or knew about it, really,” Wilson (Luther, The Affair) said after a PBS news conference last month. “I mean, we’re very sporting as a family, but we weren’t into acting or writing. For me to choose that profession was really quite odd.”

Not so odd as the story the British actress helps to tell in Mrs. Wilson, a presentation of PBS’s Masterpiece premiering Sunday in which she plays her late grandmother Alison Wilson, who discovered after her husband’s death that the man she considered herself married to for some 20 years, and with whom she’d raised two sons, was a bigamist.

And not just any bigamist: Alexander “Alec” Wilson (Iain Glen, Game of Thrones) was a prolific writer of spy novels who’d worked for Britain’s MI6 during World War II, spent time in India, as well as in jail, and over the course of his 69 years acquired multiple families whom he managed to keep quite separate, as well as a service record that remains a bit of a mystery, though it’s been claimed he was fired from MI6.

“MI6 still won’t release records. It’s ‘case-sensitive,’ apparently,” Wilson said. “So we’re still digging and asking what his involvement was with them and what he really got up to."

Finding out about the secret life of Alec Wilson, through the first installment of a two-part memoir Alison wrote for her family, solved at least one mystery for the granddaughter born nearly 20 years after his death. “I was like, oh, well, he was like the greatest actor of all of us,” Wilson said. “That’s obviously where my creativity comes from. I mean, he was performing all the time in his own life.”

Though nine of his novels were reissued a few years ago, they’d earlier been “wiped from history," she said. “Two major publishing houses … they had wiped records of him. So we couldn’t find them anywhere,” though the family had the books as well as published reviews.

“They’re good fun. They’re of their time,” she said of the novels, the first of which was originally published in 1928. “There’s great female characters. He writes very interesting, strong women in them."

Wilson is in previews for Broadway’s King Lear, in which she plays both Cordelia and the Fool opposite Glenda Jackson’s Lear — the play officially opens on April 4 — and U.S. audiences will get to see her return to Luther as the brilliant sociopath Alice Morgan when the fifth season of the detective drama starring Idris Elba comes to BBC America on June 2.

Alice is “back with a vengeance,” she said, and “as dramatic and as naughty as ever.”

As Alice, "I get to sort of do everything everyone wishes they could do and get away with it,” she said, laughing. “No, she’s ridiculous. And I’m working with Idris. Idris and I have a great little chemistry, and [we’ve] been working on those characters for eight years, so it’s really fun to return to it and play more.”

>>READ MORE: Idris Elba and Ruth Wilson talk about starring in ‘Luther’

Stepping into the shoes, and period clothes, of Alison Wilson — who happens to share a first name with Wilson’s late character from The Affair — wasn’t nearly as much fun.

“Playing her was really tough. I mean, I’ll never do anything like that again. It was weird. And I think I was really in slight denial about it for a while building up to it, and the stress building up to it was quite strange," Wilson told reporters during the Television Critics Association’s winter meetings.

“When the carpet was coming out from under her feet in the ’60s [after her husband’s death], I found that so difficult to play. I felt really self-conscious, uncomfortable. I didn’t want to be seen by the camera. I had this weird adrenaline going through my body. And I kind of think it was Granny passing through me,” she said.

“There were weird moments, as well, like giving birth to my dad, which was really bizarre," she said.

And then, of course, there was the “huge responsibility" of trying to manage the expectations of what were essentially four families, Wilson said. "I would make sure they saw scripts as they were coming in, and if they had any concerns, to let me know. They were always so amazing with Anna [Symon, who wrote the script]. Their notes were things like, ‘Oh, well, it wouldn’t have been that sort of plane in those days.’ ”

“I was expecting like, ‘Don’t go down there. That’s too dark. I don’t want that revealed about my mom or my dad,’ " Symon said. "But it was more like, ‘No. They wouldn’t have smoked that. It would have been a pipe, not a cigarette.’ I was like, “OK, I can change that easily.’ ”

What struck Symon in doing her research was “that all Alec’s children absolutely adored him as a man, and whatever faults he’d had and how much he’d let down his wives, he was a brilliant father.”

“The way his kids talk about him, whether it’s Dennis, who is 97, or it’s my dad, they have such fond memories of him,” Wilson said. “He’s obviously incredibly present in the moment. So when he was with you, his light shone upon you, whether you were kids or a wife. When he wasn’t with you, he was with someone else doing that. But I think that they all felt loved by him. They all felt enormously loved by him. Maybe he just had an enormous capacity to love a lot of people.”

As DNA testing continues to uncover some families’ best-kept secrets, Mrs. Wilson, whose three parts will air over the next two Sundays, feels especially timely.

“I think it’s touched a nerve,” Wilson said of the show. When it aired in Britain, “suddenly, publicly, people were talking about secrets and lies within their own family and how much do you really know the people that you’re related to.”

Wilson now counts as kin some 55 people related through Alec. The discovery of his deceptions has "created this bizarre story and this amazing family,” she said.

“This show is about family, it’s about secrets, but it’s about forgiveness, and it’s about love. [As] my grandmother wrote in her memoir, ‘This is a love story.’ ”

Mrs. Wilson on Masterpiece. 9 p.m. Sunday, March 31, and Sunday, April 7, WHYY12.