Derry Girls writer Lisa McGee on creating the Irish Spice Girls and working with Paul Mescal in The Deceived

Derry Girls is undoubtedly brilliant. McGee’s semi-autobiographical depiction of a group of teenagers growing up in Northern Ireland during the Troubles has been a huge hit, thanks to its nostalgic 1990s soundtrack and fashion, brash characters, and genuinely laugh-out-loud jokes (Michelle’s take on Irish history: “We got the gist. They ran out of spuds, everyone was raging”).

But other brilliant shows don’t get such a visceral reaction. What is it about Derry Girls that inspires such devotion? “I was sort of joking about the Spice Girls, but there is something about these five being very definite individuals,” says McGee. “People choose which Derry Girl they are. There’s something about that clear ‘She’s my favourite one’ that young people love.”

That character definition is certainly one of McGee’s great skills. She recently tweeted a hilariously believable list of celebrities that each Derry Girl would have fancied – including Robbie Williams for Michelle and Lisa Bonet for Clare. It’s clear she spends huge amounts of time building up her character’s back stories, interrogating every inch of their personalities.

“I can’t move on until it’s right,” she admits. “I spend a lot of time thinking of names for people and even their pets, and detail about their lives. I really know now what they would do and how they’d react to any situation.”

Her other gift is for sparkling dialogue: a skill she has been honing ever since she was a little girl, listening to adults around her and writing sketches about them. “I’ve always loved finding those little expressions which make dialogue sound natural,” she says. “Weirdly, it’s harder to make dialogue sound natural than it is to make it sound poetic, so I spend a lot of time listening to people, waiting for those ticks and quirks.”

On the surface, McGee’s new venture might seem a significant departure from Derry Girls, which has a third series written and ready to be filmed when lockdown measures ease. The Deceived is a four-part Channel 5 thriller about a manipulative Cambridge University professor (played by Emmett J Scanlan, of Peaky Blinders, The Fall and Butterfly), a mysterious death and a ghostly house.

So far, so different, except that it’s really a return to her roots, as McGee’s background is in drama: her first job was as a playwright at the National Theatre in London, before she found herself working on the BBC’s Being Human and Channel 4’s Indian Summers.

“I did a lot of stuff before Derry Girls,” she says. “Some of it did OK and some of it didn’t. It’s been a long journey to get here, but it was good for me. You hone your skills when you’re realising someone else’s vision.”

And despite The Deceived being a totally different genre, there are similar themes that link back to Derry Girls. Her professor, for example, is an Irishman having an affair with an English girl; Derry Girls mines much humour from English-Irish relations.

McGee admits it’s an area of particular interest, thanks partly to her marriage to the English actor and writer Tobias Beer, her co-writer on The Deceived. The couple met in 2013 on a night out with mutual friends and were married two years later by Beer’s father, a clergyman from Yorkshire who was then the retired Archdeacon of Cambridge.

“I’m very interested in the English-Irish thing,” says McGee. “The similarities and the differences. A lot of my inspiration comes from going home to Ireland and just listening to the stories people tell. Toby has a different take on it, as an outsider. When he first started coming with me, he was fascinated by the way people would tell ghost stories and take it very seriously. That fed into The Deceived.”

The couple were also influenced by a love of old movies like Dial M for Murder, Rebecca and Gaslight with their themes of jealousy, obsession and illicit affairs. From their London home, Beer, 43, joins the Zoom call to explain more.

“Lisa seemed quite interested in my past when we got together,” he laughs. “I discovered that if you marry a Derry woman, they don’t like the idea that there’s been any women before them. So we talked about that and we became interested in the idea that a mistress’s position is quite precarious. If you end up with a man like that, you know they’re capable of an affair and that they’ll probably do it to you at some point.”

In the end, the discussions led to the story of Dr Michael Callaghan, a professor whose wife Roisin (Catherine Walker) dies in mysterious circumstances. Michael’s student lover Ophelia (Emily Reid) visits his home in Ireland and becomes suspicious about what happened to Roisin and what her marriage was really like.

The cast also includes Ian McElhinney and Louisa Harland from Derry Girls, as well as a certain Paul Mescal, who shot to fame as Connell in Normal People. Beer recalls, “Our casting director told us, ‘You’ll be very lucky if you get Paul, he’s going to be a star.’

“I’m mortified, because I had conversations with him on set and having now seen Normal People, the idea that I could tell him anything at all is just embarrassing! He has this amazing quality, he does so little but has incredible depth behind a relatively impassive face. It’s very rare. And he’s potentially a knight in white armour in this, so people will hopefully enjoy that.”

Working together as a couple seems rather brave in itself, but when they first started writing four years ago, they had a newborn baby, Joseph, and when the series finally began to shoot in October, McGee, 39, had just given birth to their second child.

“The trickiest thing is maybe how full-on it is,” she says. “When your partner’s not involved in your writing then you have to switch off at some point, but if you’re both involved, it can become all you talk about and that’s not great.

“We didn’t know where to draw the line. We were feeding the baby and going, ‘I think we should change that line in episode three.’ Dear Lord! We should have just stopped and watched an episode of Columbo.”

“Yeah,” adds Beer, “but it was inevitable that we’d write together at some point because all we talk about is TV. It’s constant, but at least if we write our own thing then we’re getting something out of it.”

This interview originally appeared in the Radio Times magazine. For the biggest interviews and the best TV listings subscribe to Radio Times now and never miss a copy. If you’re looking for more to watch, check out our TV Guide.