Boy Meets Girl: Britain's first mainstream sitcom to cast a transgender actress in a lead role

Boy Meets Girl, an engaging new BBC sitcom, charts the burgeoning romance between a young man called Leo (played by Harry Hepple) and an older woman named Judy (Rebecca Root). In the pre-titles sequence, the couple are on their first date at a cosy restaurant when Judy utters the words: "I was born with a penis."

It's quite an opening gambit, but the sitcom which follows is neither sensationalist nor deliberately provocative or banner-waving. Written by newcomer Elliott Kerrigan, Boy Meets Girl is simply a touching love story. The fact that Judy is transgender is only one element in a funny and frequently tender romance.

The makers of Boy Meets Girl emphasise that the show should be seen as a love story, not a lecture. Kristian Smith, the executive producer who has nurtured the project from its gestation many months ago all the way to its broadcast on BBC2 tomorrow, says: "Elliott's script leapt out at me because it's a very human story. Clearly, it portrays an area that we haven't done before, but fundamentally it's a romcom. The love story is the real motor."

The appeal of the show for Root, a transgender actress who delivers a beautifully nuanced performance as Judy, was similar. Boy Meets Girl never makes a song and dance about the fact that Judy is transgender. "I don't know if 'normalisation' is the right word, but it's lovely just to see a trans woman having a relationship with a cisgender [someone whose gender identity coheres with the sex they were assigned at birth] guy. There are a couple of bumps, but it's really no big deal. When I first read it, I thought it was genuine and human and wonderful."

Smith says that they never considered doing the show without a transgender actress as Judy. "That's an essential part of this. It has to be an authentic story. It reflects a real experience. We saw a lot of people for the role of Judy, but Rebecca was always towering above the others. We thought she was so right. She has this personable quality that is vital for the part. We needed that Everywoman element for the spirit of Judy, and we discovered that in Rebecca. We never wanted it to be heavy-handed. We just wanted it to be real and human."

Leo, who comes from a down-to-earth background in the North-east of England, understands Judy from the start. In the opening restaurant scene, as the couple tentatively get to know each other, he says to Judy: "So you were born in the wrong body." To which Judy replies: "It was like being born in prison, and never having a release date."

Boy Meets Girl was developed by the BBC after picking up the Trans Comedy Award, run by BBC Writersroom and the media education group All About Trans to find a script that portrayed transgender characters in a positive way. It does not preach but merely presents a pair of loveable characters and hopes that we fall for them as they fall for each other. In that way, it sidesteps the word that sounds the death knell of all comedy: worthiness.

"I'd hate there to be a whiff of preachiness – I'd be bored," says Kerrigan, who is not transgender but has become good friends with Root and taken advice from her. "It would turn viewers off if it became a lecture. Everything that's said in this series is in character. There's no exposition. The characters will draw people in, not the issues."

Root, 46, who stars with Eddie Redmayne in his new movie, The Danish Girl, about Lili Elbe, one of the first known recipients of sexual reassignment surgery, was on hand as a sounding board. "I dipped in here and there, but I didn't need to say, 'You can't have that!' because Elliott's writing is so truthful."

The series underscores that not everyone is up to speed on the correct terminology, though. Leo's family are initially all at sea. "I hope we share the process of discovery of a family who learn to understand something of the trans experience," says Root.

"It's interesting because Judy has so much more chutzpah than I have. She's out there, and she's upfront– all the things I'm not. It's lovely to have permission to step into her shoes. … Any actor brings something of themselves to the part. You mine your own history. Not to get too Method-y about it, but there was definitely a moment which touched my own background – that 'born in a prison' line. That really resonated with me."

By chance (they were broadcast after Boy Meets Girl went into development) two award-winning American shows, Transparent and Orange Is the New Black, also feature trans characters – as do the movies Dallas Buyers Club, Transamerica and Hit & Miss. Can such works ever change viewers' minds? "I hope so," Smith says. "We're there to entertain and to make people laugh, first and foremost. But aren't the greatest lessons taught through humour?"

Kerrigan cites his influences as My So-Called Life and Will and Grace ("I'd watch that with my Grandma") and is already working on a second series. "I want to say you can smuggle things in. Comedy is a very good way of getting ideas into people's living rooms."

Root agrees: "I like the idea of smuggling yourself into people's living rooms – although perhaps that sounds a little creepy. But the great thing about comedy is that it disarms people. It's only afterwards that they think, 'OK, there was something else there apart from just a good chuckle or a warm and pleasing experience.' It's a wonderful medium to reveal other stories."

Indeed, comedy can touch on truths more effectively than other genres. "I'd agree with that," says Hepple, 31, who previously starred in Misfits. "All the greatest comedies have transcended the genre and have ideas that have lain under the surface. I'm not going to name them because then it'll sound like I'm trying to compare our show to them, but comedy really can tell us things that other genres can't. You make [people] laugh – then you break their hearts. That's the way the best comedy works."

"Maybe people will come with a certain prurient kind of curiosity, but that's great," says Smith. "Whatever drives people to Boy Meets Girl, I hope they'll all fall in love with it in the same way. I believe that romcom element is going to hold people."

'Boy Meets Girl' begins on BBC2 tomorrow