We've been discussing the actor's playwriting debut, a dark comedy about a trainee priest losing his faith and returning from the seminary to find his Glaswegian family falling apart. Nobody Will Ever Forgive Us is one of four pieces by new writers co-produced by the Traverse and National Theatre of Scotland for this month's Traverse Debuts season. It reunites Higgins, 44, with the NTS's director of new work, John Tiffany, who directed him as the writer and sergeant in the original production of Black Watch.
Raised in Wishaw by an atheist father and Catholic mother, Higgins left the seminary at 17 when it came out he'd been seeing a girl. Yet Catholicism won't leave him. He sees Nobody Will Ever Forgive Us as a portrayal of "a typical working-class British family. But obviously it's Catholic all over, those notions of God and guilt."
Higgins sought to be a missionary rather than a parish priest. "I wanted to go out and save the world," he says. "When people discover I went to a seminary, they often ask me about abuse. But my experience was the exact opposite. Like Patrick says in the play, it's the best thing that ever happened to me, certainly up to that point. I really didn't want to leave and it had more to do with girls than it does for Patrick. But the doubts grew, like tectonic plates pushing against each other. Something had to give."
We're in a bar in Glasgow's Merchant City. Higgins has the day off from filming Hope Springs for BBC Scotland, a comedy-drama about four female criminals hiding in a remote village. He plays the local policeman, caught in a love triangle between his fiance (Ronni Ancona) and the gang's leader (Alex Kingston). "It's got scenery, romance, comedy, dismemberment and murder," he says, approvingly. "It's very ambitious."
Breaks like today will afford him the chance to watch Tiffany conduct rehearsals of his debut play at the Traverse. "We're quite different, and I hope we complement each other. John did an astonishing job with Black Watch. I never thought it would be the most successful show I'd ever been in. Quite the reverse. Cammy being carried around as he narrated the history of the regiment was a disaster in rehearsals and I remember saying, 'When are they going to cut this?' And then we did it before an audience and they went wild. Actors can get very tied up in their own characters and John is quick to remind you what the audience is feeling."
For viewers of the BBC's The Thick Of It, Higgins will always be Jamie, the psychotic lieutenant to Peter Capaldi's spin doctor. I ask how he summoned the necessary fury for the character. "I'm afraid that terrible rage comes easy to me," he laughs. He reprises Jamie in In The Loop, the big screen adaptation due next May, with James Gandolfini, Tom Hollander and Steve Coogan alongside the original BBC4 cast.
"I have a speech, I don't know if it's still in, about the film There Will Be Blood. Jamie's really disappointed because there's 'no f***ing blood'." As Black Watch's sergeant, Higgins toed the official line, addressing his soldiers' grumbles with an unequivocal "it's our turn tay be in the shite". And in In the Loop, Jamie is likewise just following orders. "Our job is to sell whatever the Prime Minister wants us to sell. If Jamie was asked to be anti-war, he would be rabidly anti-war. Whatever's required, so long as it's rabid." After Black Watch, though, which was directly based on squaddies' testimony, the actor could never be so uncritical as his onscreen realpolitik rottweiler.
"I'm hesitant to say this because of how it would look out of context, but it made me believe in national service for everybody," he says. "If the children of the English middle-class had been going abroad to die, I don't believe we'd ever have gone. I never thought I would think that. I don't believe in national service to knock sense into young people, but if you're going to have an army it should be representative of the country. There shouldn't be any cannon fodder."
Nobody Will Ever Forgive Us echoes this sense of limited opportunities for the working-class. "I started writing it about five years ago. I'd been talking to somebody about my dad and the extraordinary way that he spoke, very elliptical and with rhetorical questions. When he wanted to, he had a fantastic vocabulary. I just started to try and write him, really. He quoted poetry a lot. In another generation he would have been another person. As it was, he was an alcoholic labourer."
Despite recent stage appearances in Scotland, such as 2006's The Tempest at the Tron and 2007's NTS production of David Grieg's Damascus at the Traverse, Higgins has lived in London for more than 25 years, after graduating from the Central School of Speech and Drama. He met his wife, actor Amelia Bullmore, in a 1992 production of A View from the Bridge in Manchester.
"That was tricky," he recalls. "I'd already fallen for her by then. But I couldn't tell her because we were playing lovers and I thought if I asked her out and she said 'no', it would f*** it up completely. So I was torn between declaring myself and just getting on with the play."
He feigns regret that their two daughters wish to follow their career path. But he hopes "to help them do whatever they want and not be prescriptive. Besides, where people start out in life is not necessarily where they end up."
Nobody Will Ever Forgive Us is at the Traverse, Edinburgh, 20-29 November, tel: 0131-228 1404.