As the Pet Shop Boys pop musical opens in London, they explain what inspired them to take on the West End

It’s hard not to laugh when Neil Tennant tells you he’s worried about becoming a luvvie. Not because he says it with the sort of wry smile that suggests he’s joking, but because — in the 15 years since his band, Pet Shop Boys, had their first hit — the posh-spoken, slightly camp singer has always seemed more like a luvvie than a pop star.

“I’ve started to call people ‘darling’,” frets Tennant, sitting in the restaurant of London’s Arts Theatre. “I used to use the word semi-ironically, but recently I’ve noticed it cropping up of its own accord.” “Oh, it’s very infectious,” warns Chris Lowe, Tennant’s musical partner.

“You have to be on your guard at all times. The same thing happened to me with ‘man’. Now, often in a club situation, it just slips out. It’s so easy to get into, so hard to get out of.”

Tennant looks genuinely appalled. “Man!” he gasps. “You? Oh, stop it! That’s ridiculous.”

Pet Shop Boys talk like this all the time. Given half a chance, they turn even the most mundane conversation into a mini melodrama. It’s no wonder that the pair have finally decided to swap the pop charts for the theatre. On Thursday, Closer to Heaven, a musical Tennant and Lowe have co-written with Jonathan Harvey, the man behind the BBC comedy series Gimme Gimme Gimme and plays such as Beautiful Thing, opens at the 350-capacity Arts Theatre in Covent Garden. And by all accounts, it won’t be like anything else in the West End.

“It’s an experiment,” says Tennant. “We wanted to see if our kind of music — electronic dance pop — would work in the theatre. We’re also trying to attract a new audience to the West End. There are so many people out there whose lives have nothing to do with the theatre. The last time they went was to see A Midsummer Night’s Dream because they were doing it at O level.

“They’ll go to rock concerts or clubs — which both have huge elements of theatre in them — but never to a play or a musical. We thought if we came up with something young people can relate to, maybe we’ll get them to come. At least, that’s the plan.”

Closer to Heaven is certainly contemporary. Not only does it boast 19 new Pet Shop Boys songs, it tells the story of Dave, a young, naive, potential pop star, who comes to London from Ireland, falls for both a girl called Stacey and a male drug dealer called Mile End Lee, and gets involved in the city’s glamorous club scene. Frances Barber plays the Seventies rock-star-turned-nightclub owner Billie Tricks, a character based on the Velvet Underground’s Nico, Paul Keating — who has played Tommy in the West End — is Dave and the Liverpudlian theatre and television actor Paul Broughton is Bob Saunders, a flamboyant pop manager with plans for world domination. It’s a far cry from Cats.

“A lot of people thought we were mad to do a musical,” says Tennant. “The general perception of musicals is that they’re naff. Hopefully, we’ll prove they don’t have to be big tourist attractions full of show tunes.”

Five years in the making, Closer to Heaven was conceived after the drama department at the BBC suggested that the Pet Shop Boys hook up with Jonathan Harvey, who had named his first TV play West End Girls — about two East 17 fans who come to London to try to meet Brian Harvey — after the band’s debut hit single.

“I had never seriously considered doing a musical until the BBC suggested it,” says Harvey, who clearly clicked with Tennant and Lowe. “I love music and using music dramatically, but I had never worked with anyone before.” When the BBC project came to nothing, the trio decided they still wanted to do a musical, only this time for the theatre.

“We had been to see Jonathan’s play Beautiful Thing in the West End and loved it,” says Tennant. “After we met him, we started going to all his plays when they came out. There was one called Boom Bang A Bang, about a load of people sitting round watching the Eurovision Song Contest. It’s about the year Britain was represented by a rap record and everyone said what a disgrace it was. It’s a funny play. When we saw that, we knew we had to work with Jonathan.”

Harvey came up with the initial concept — a love triangle set in a nightclub. Together, they filled out the story, came up with the characters and planned where the songs would go. They rented a house in Sussex with a studio, where, over the course of a year, they would go together for a week at a time. While Harvey plotted the scenes and wrote the dialogue, Pet Shop Boys would be in the studio, composing the music.

“The biggest challenge was marrying their music and my dialogue,” says Harvey. “It was a lot harder than we thought it would be. We certainly didn’t get it right first time.”

“Trevor Nunn at the National read our first draft,” recalls Tennant. “We thought it was good, but apparently it wasn’t. Trevor told us there mustn’t be a sense that the play stops for the songs, which is how we had written it. It has to be a seamless mix.” Three drafts later, they finally got it right. Then they did a workshop, a rough rehearsal with a basic set and temporary cast. “I thought, ‘Why are we bothering with a bloody workshop?’ ” says Lowe. “We’d spent so much time on the script already. But it was the best thing we could have done. We suddenly realised that what looks good written down won’t necessarily work on stage. There was almost no connection between what was on the page and what we were watching.”

Their second big problem was casting. “We wanted all the young characters — mainly 18 to 21-year-olds — played by people as close to that age as possible,” says Tennant. “We thought London was full of incredibly talented kids. We were wrong.”

“The problem was that everyone had to be able to sing, act and dance,” says Harvey. “There were a lot who could sing and thought they could act, or who could act and thought they could sing, but very few who could do both. By the time we filtered out people who were the wrong height or had the wrong look, there was hardly anyone left. It was a nightmare.”

Their big coup, however, was getting Frances Barber. “We always had her mind,” says Tennant, “and as soon as she came in, she was fantastic. She helped us develop the part of Billie Tricks. We made it bigger because she was so good in the role. There’s definitely potential for a spin-off there.”

Produced at a cost of around £500,000, Closer to Heaven is relatively cheap for a musical. Although they are not actually performing the songs — there will be a cast album, produced by New Order collaborator Stephen Hague — Pet Shop Boys clearly see Closer to Heaven as a natural extension of their pop career.

“Our own tours have always had a theatrical basis,” says Tennant. “We have made a point of working with people from outside music, directors or architects or whatever. We have talked about doing a musical ever since we became successful because we felt the sort of songs we write would lend themselves well to the theatre, whether it was us performing them or someone else.”

In the past, Pet Shop Boys have written for Kylie Minogue, Liza Minnelli, Dusty Springfield and, er, Patsy Kensit. Composing songs for fictional characters, claims Tennant, is pretty much the same process. Four years ago, Pet Shop Boys took their own music into the West End when they performed a series of sold-out shows staged at the Savoy Theatre.

“Ironically, that wasn’t at all theatrical,” laughs Lowe. “It was a collaboration with Sam Taylor-Wood, so more of an art piece. It was just us trying to be YBAs. Sorry, OBAs.”

For Tennant working on Closer to Heaven fulfilled a childhood dream. “When I was very young, my grandfather used to play me the soundtrack to Oklahoma! on his stereogram,” recalls Tennant. “That made a real impression on me. I started watching musicals on television and going to see them at the Theatre Royal in Newcastle, where I grew up.

“When I was nine, I even wrote my own musical with a girl from school. It was called The Girl Who Pulled Tails, about a girl who got into trouble because she went up to cats and pulled their tails. The pair of us performed it in my back garden one afternoon. I don’t remember much about it. There is one scene that sticks in my mind though, which the girl herself insisted on doing. It was where she took off her dress to reveal she was wearing a black bra. What can I say? We were very innocent in those days.”

·  Closer to Heaven is in preview at the Arts Theatre, WC2 (020-7836 3334), and opens on Thursday. Jonathan Harvey’s Out in the Open is at Hampstead Theatre (020-7722 9301) until June 16