PENNED in the room above a bar owned by former dockers, Brick Up the Mersey Tunnels is about as Liverpool as it gets.

Since its debut in 2006, more than 100,000 tickets have been sold for the show that treats the Wirral-Liverpool divide with a dose of comedy, singing and daft characters.

But the audience hasn’t all been from the cityside of the river, reveals co-writer Dave Kirby. Some have even ventured over to the Royal Court from their salubrious residences on the peninsular.

“The Wirral gets lambasted but so do Scousers so the cross-river banter is well even,” says Kirby, who is well known locally for his poems expressing his passion for Liverpool FC.

“The doctor I go to, he’s actually seen it – that’s when I knew it had crossed the class barriers.

“And then I saw a man who goes to the match on Saturdays and he said ‘Alright Dave! I’ve never felt as proud to be a Scouser in my life as when I came out of that play’.”

None of this would have come about if it hadn’t been for a “particularly condescending letter” printed in the Daily Post’s sister paper, the Liverpool Echo, back in 2002. It was written by a Heswall resident.

“She was slagging off the Liverpool accent and she’d worked here for 30 years,” says Kirby, clearly still indignant about the subject.

He and co-writer Nicky Allt, whose new play One Night in Istanbul opened at the Empire this week, were sitting in the Casa bar on Hope Street at the time.

“Everyone started ranting about the Wirral and this letter and out of all this mayhem came this shout – ‘I’d love to brick up the Mersey Tunnels’.

“The dockers gave us a room upstairs in the Casa bar and Nicky and I started to meet there every Monday to write this surreal panto. The first draft of it was more of a political satire. We were angry when we wrote it.”

Director Bob Eaton brought along his experience of working at the Everyman in the 1970s and Kirby recruited his old school chum Andrew Schofield into the cast. Allt and Kirby were pleased with their creation but hadn’t anticipated its reception.

“We knew it would work in this city because it’s got a really strong Scouse parochial pride, but we didn’t expect it to become one of the most successful plays of its generation. That’s mindblowing.”

Two more of Kirby’s plays– Lost Soul and Council Depot Blues – have since made it on to the Royal Court stage to the delight of Brick Up fans.

But the greatest pleasure in his success, he says, is that he has encouraged people into the theatre who would normally be put off.

“I like Shakespeare, Arthur Miller and Steinbeck’s one of my favourites,” he says, “but for every one of me there are 10,000 out there who aren’t like that.

“I was in the building trade for 25 years so I know what I’m talking about.

“People aren’t going to discover Shakespeare in their 40s – they just want to escape from the life they’ve been given.

“The Everyman & Playhouse rejected Brick Up twice so I’m under no illusions about theatre – it’s a very middle class medium. Brick Up is populist, working class theatre and I think that’s the new rock ’n’ roll.

“The important thing to me is that it’s getting thousands of people into theatre who’ve never been before. That’s the magic of it.”

Brick Up the Mersey Tunnels is at the Royal Court, Liverpool, from July 10 to August 22.