In June, a few weeks after filming finished on the gruelling nine week shoot for Mrs Wilson, Ruth Wilson and the extended Wilson clan gathered in Southhampton.

It was there that Ruth’s grandfather Alec lived with Gladys, the first of his four wives, and it was there that he was buried. And so it was there, then, that the extended Wilson family, sprawled across Alec’s four marriages and seven children, decided to come together to watch the miniseries that Ruth had produced and starred in about their family’s unique history. There was champagne and speeches and a party atmosphere. And then there was the opening of a floodgate of emotion.

“There were three or four minutes of silence at the end and everybody was crying,” Ruth recalls. “In a good way!” she adds quickly. “It felt like this amazing sharing of secrets and this experience which had united us all. Cousins were hugging uncles. From all different places, we had all found each other.” 

A photograph of the 45 living Wilson family members was taken that day to be screened at the end of the miniseries, and Ruth admits that looking at it brings her to tears. “My grandmother never knew that we all met,” she explains. “She died 12 years ago. I wonder what she would have thought of it… I find it incredibly moving.” 

The third and final episode of Mrs Wilson airs tonight, the completion of Ruth’s deeply personal miniseries about her grandmother Alison’s relationship with the husband she knew as Alec. They met while working together at MI6, when she was 21 and he was 48, living in London and raising two sons Gordon, Ruth’s uncle and Nigel, Ruth’s father.

After Alec died in 1963 of a heart attack, Alison discovered that he had three other wives, five other children, and that he had misled her about the nature of his work with MI6, his age, his income streams and even his name. (On his marriage certificate to his first wife he is listed as Alexander. Ruth and her family refer to him as Alec.) Alison kept these secrets until just before her death in 2006, when she bequeathed her sons the memoir she had written about their father. 

The following year all of the Wilson children and grandchildren met for the first time, and have stayed in contact ever since. Within Ruth’s family, at least, the story has always been “vaguely funny, weirdly, because it’s so absurd.” So much so, that for the last decade Ruth’s immediate family had told her it would make a fantastic television show.

Mrs Wilson focusses on Alison’s story, with Ruth starring as her own grandmother. But Ruth consulted Alec’s four surviving children every step of the way, she says. “They read scripts,” Ruth says. “I made sure they were all happy with what we were doing and how we were dramatising various members of their family.” 

As a result, Ruth has never felt closer to her relatives. “I feel so close to my grandmother and to my dad and my uncle,” she says. “Having to get underneath their experience and to live and breathe it every day I’ve had much more empathy and understanding of who they were and are.” 

She recounts the enormous connection she felt with Otto Farrant, the actor who plays a teenage version of her father in the miniseries. “It was so weird, I felt such affection for those boys it was really interesting. There were many moments where I felt something passing through me when I was sitting in my grandmother’s experience.”

Like her spirit? “I dunno if I believe in anything, but definitely I’ve felt her within me and looking over and me during [the making of] it,” Ruth says.

To that end, it was important that Mrs Wilson never blames Alec (played in the series by a raffish Iain Glen) or Alison for the decisions that they make. “People might be amazed but it’s true, you can still love a man who has acted so horrifically in so many ways seemingly with no reason,” Ruth explains. “She wasn’t destroyed by a bad man. She was strong enough and she came through. Other people might question it but that’s for them to judge. I didn’t want to judge her feelings, I just wanted to portray them.”  

Now that the miniseries is coming to an end, Ruth’s overwhelming emotion is one of release. “I’m still processing it,” she says. “It’s been really hard, actually [to get out of it]. During it was really tough, too. I didn’t want to be looked at on the screen. It was a very odd experience.”

Next, she’ll be in the BBC’s His Dark Materials miniseries as the dastardly Marisa Coulter before heading to New York to play Cordelia opposite Glenda Jackson’s King Lear on Broadway. “[Mrs Wilson] does feel like an ultimate thing to do,” she laughs. “Performance wise, I don’t know how I can match it, really.” 

Yes, she’s “dead chuffed” with the series’ critical acclaim, but mostly she’s proud of how the drama has helped relieve some of the shame within her family and bring its disparate members together. 

“Strangely, within our family there isn’t a huge amount of anger,” she says. “For me, there’s a lot of hope in this story. Our family has found each other, and all the suffering and the betrayal led to a family unity… I think of my grandmother’s hope for forgiveness, of good coming from bad. I think that has happened.” 

The third and final episode of Mrs Wilson will air on BBC One at 9PM tonight. The full miniseries is also available on BBC iPlayer.

Images: BBC/©WP Films Ltd