Dressed in a tatty white T-shirt, sofa-worn sweatpants and a pair of much-scuffed trainers, David Threlfall is clearly attired, today, for comfort. His hair is short and sort of blonde, which of course looks preposterous atop a 51 year-old with a face as lived-in as his. But, as he later explains, it's for a TV movie he is currently filming about Princess Margaret, in which he plays Prince Philip in 1970.
"So it's purely temporary, trust me," he says, pulling on a forelock straight out of Dickens. Right now, though, in this central London hall, Threlfall, along with fellow actors Aidan Gillen and Jonny Lee Miller (Queer As Folk and Trainspotting, respectively), is in rehearsals for Someone Who'll Watch Over Me, the Frank McGuinness play inspired by Brian Keenan's experiences as a hostage in Beirut. As I arrive, Gillen and Lee Miller are in the middle of a particularly dramatic scene, which Threlfall and I watch together, covertly, through a side window. It looks, I tell him, pretty intense.
"Yes, well, it is - in parts. But it's not just intense, you know? It's funny, too, it's... it's everything." He begins to frown. "Nothing personal, but I hate people who feel the need to generalise, to compartmentalise. Why do they do that? It drives me nuts." I try to explain that I was referring specifically to the scene just witnessed, but Threlfall has now slipped, as shall prove his wont, into Frank Gallagher, the splenetic character he plays in Channel 4's Shameless.
Thus, sudden irritability will not be suppressed. "It's like when people call Shameless a comedy drama. It is not," he says, lips thinning, "fucking comedy. It's drama, just drama. Got it?" Suddenly, he brightens.
"Fancy lunch?" he asks.
A quarter of an hour later, we are seated not in The Ivy but a bustling branch of Benjys cafe, at a window table, Threlfall working his way through a plastic bowl of coleslaw and glugging enthusiastically on a Tango. The actor makes for gregarious company, at once intense, vague, skittish and serene. He listens earnestly to questions, then floats off on unpredictable tangents, intermittently loses his patience and quickly reins it in again. Often, it is difficult to keep up with him. Only occasionally will he make full eye contact, and when he does, you rather wish he hadn't, as it is normally accompanied by ire.
"People say I'm famous these days, that Frank Gallagher is iconic, and that's good. Of course it's good. But it's not like I've suddenly appeared out of, I don't know, the ether," he gabbles. "I've been around the block, you know. I've had all kinds of nominations - BAFTAs, Tonys, Emmys - not that I've won anything, mind, but still. Shameless is, I suppose, opening doors for me, but it's not as if they were all previously shut. My CV, which occasionally masquerades as evidence of my career, will show you that I have a wide body of work under my belt." Nevertheless, it is Shameless that has brought him wide public recognition. And fittingly, too, because Threlfall is magnificent as Frank Gallagher, the lovable and loathsome drug-taking Mancunian father of, at the last count, eight, whose antics have become steadily more deplorable over the past two series. It is clearly the role of a lifetime, and he has suggested in the past that preparation for it has involved not just learning lines but also indulging in copious amounts of drink, drugs and sex. Now, he chooses to claim otherwise.
"What it is is this," he begins. "I'm an actor. I slip into Frank in the morning, and slip out at night. I don't want to say too much, give too much away as to how, exactly, I do it..." and this makes him sound very grand indeed, "...but let's just say I can turn it on because - because it's what I do." However he chooses to mystify it, his performance has fully entered the national consciousness, prompting broadsheets to suggest that, in reference to that other fiftysomething character actor recently bestowed with proper movie star fame, he is now about to "do" a Bill Nighy. But Threlfall, perhaps predictably, considers to be this nonsense. Another one of his pet hates is people who make comparisons.
"Excuse me, but what does do a Bill Nighy mean, exactly? And why Bill Nighy? Don't get me wrong - lovely man, respect him hugely - but I'm nothing like him." What it means, I begin - but that's as far as I get.
"I hate labels. I hate being called, you know, whatever - character actor, leading actor, film star - it's all bollocks. I am what I am, some bloke playing around in the toy cupboard. If I'm starting to get noticed for it, great, but my feet are very much on the ground." He then says something about the play he is currently rehearsing, about how its themes vaguely mirror the actor's life in general. It is a somewhat muddled comparison - and pretty rich for someone who claims to hate comparisons in the first place - and when he finishes speaking five minutes later, he looks quite lost.
"Anyway, I kind of segued there," he says. "Where were we? What were we talking about?" Search me.
David Threlfall was born half-a-century ago in Burnage, Manchester. His father was a builder, but any hopes that his son would follow the family trade were quashed when Threlfall appeared in the school play and loved it.
His father was nevertheless supportive, and relieved to see his son so uncharacteristically happy.
"I'd been having a lot of trouble with school bullies at the time," he explains. "To this day, a red mist descends even thinking about it. I fucking hate bullies, despise them." It lasted through primary school and into secondary, until his father decided to take matters into his own hands.
"We drove round to where they hung out and confronted them," he recalls, "my father telling us to fight it out now, and to let that be an end of it. And that was that. It stopped in a heartbeat." I ask him how. What happened? What was the outcome of the fight? But Threlfall, an actor who knows just how to do enigmatic, refuses to elaborate.
"Let's just say it ended. You don't need details. My dad's methods were... they were effective." After school, he attended art college in Sheffield, then studied drama at Manchester Polytechnic. Upon graduation, he went straight into gainful employment, working with Mike Leigh and Les Blair before landing a place with the RSC. In 1979, his performance as Smike in Trevor Nunn's eight-hour adaptation of Nicholas Nickleby brought him his first real success, a role he went on to replicate when the play transferred first to Broadway and then on to American television.
"My motivation," he says, "was always a simple one: to keep working." Obviously, there were many less than satisfying gigs along the way - microscopic parts in Hollywood movies like The Russia House and Patriot Games, a stint as Prince Charles in the NBC mini series Diana: Her True Story and, in 1994, a car commercial for Ford - but he was earning money, and that was enough.
"I'm not going to sit here dissing the shit jobs because that would be... wankerish," he says. "Any work is better than no work at all." Towards the end of the Nineties, Threlfall hit a dry patch. It lasted two years.
"It got so bad that I was this close to becoming a dispatch rider," he says.
"I thought, I've got the motorbike, a clean licence, how hard can it be? When you're out of work, it's a very humbling experience, and you'll do anything to keep stimulated: yoga, feng shui, running, drugs, sex, alcohol." He grins malevolently, Frank Gallagher peaking through. "Not that I necessarily tried all those things - or at least not in that order, but you get the picture, right?" He was ultimately saved from motorbike courier work by the offer of more theatre, and in 2001 drew rave reviews for his performance in Joe Penhall's psychiatric drama, Blue/Orange. And then two years later, Channel 4 called with Shameless. It was to change his professional life.
"And now, suddenly, all these opportunities have come flooding in," he grins. "It's like three or four buses arriving at once, me jumping on every last one." Abruptly, he pulls himself up short.
"But I don't want to come across as a smug bastard," he says. "I fucking hate reading actors prattling on about their good fortune. I've just hit a run of luck, that's all, nothing more." He then proceeds to downplay it by admitting that he has yet to be offered any plum film roles, something you feel he dearly wishes for. Perhaps, I suggest, it's because of his reputation. "What reputation?" he asks, eyebrows arching.
Well, when Mike Leigh directed him in 1978's The Kiss Of Death, he remarked that the actor had "a slightly surreal streak that sometimes gets in the way," while Trevor Nunn described him as "a handful. [He has] an appetite for experiment which takes things off into sometimes unhelpful directions." He nods his head thoughtfully. "Yeah, okay, I'd go along with that. I like to shake things up a bit, it's true, but that's good, isn't it? I don't set out to piss people off, but experimentation is something positive. I like to push myself and, well..." He holds up both palms as if in admission of guilt. "Okay, perhaps I can get a bit selfish at times, I'm only human. But I'm not a completely self-regarding idiot, and I don't think anyone would actually describe me as difficult. I hope not, anyway."
David Threlfall doesn't do many interviews, probably due to his hatred of the journalistic need to label people, to describe them as character actors who appear in comedy dramas. And all this talk of his recent career arc is, he says, making him feel self-conscious and boastful.
Yes, yes, things are good right now, he is happily married (to Sarajevo-born actress Brana Bajic, and has two sons, nine and five) and he will return in Shameless later this year for a third, and possibly final, series. But every actor, he argues, has his ups and downs. Threlfall is no different.
"If I'm honest, I think on a good day there is not a lot I can't do," he says, "and hopefully people will realise that now. But nothing has changed in my life, not really. I'm still bobbing along, like I always have." He looks at his wrist and finds bare skin where he expected a watch.
"Better get back to rehearsals," he says. "I'm late." He stands, frowns a final time and flees.
'Someone Who'll Watch Over Me': New Ambassadors, London WC2 (0870 060 6627), now previewing, opens Tuesday, to 18 JuneReuse content