The last time I spoke with Lenny Abrahamson, he had to explain why he took so long with his work. Adam & Paul, his era-defining study of two wandering Dublin junkies, arrived with us in 2004. Garage followed in 2007. It took another five years for the hugely acclaimed What Richard Did to emerge.

Now, like Terrence Malick, our Lenny seems to have found a new gear. The odd, angular Frank hits cinemas next week. Abrahamson is already at work on an adaptation of Emma Donoghue's admired novel Room. After that, he will move on to a film version of Sarah Waters's ghost story The Little Stranger.

How can I put this delicately? Abrahamson is still (by my decrepit standards anyway) a young man, but time makes concessions for no man. As he moves into his later 40s, has he become aware of a ticking clock?

“There is a lot of that,” he laughs. “The decision to up the ante was precipitated by the oncoming crisis that is 50. What’s scary about 50 is not 50 itself. It’s the proximity to 60. I am very aware that this goes by very quickly. If you divide it into four-year blocks you don’t get to make that many films.”

Frank marks a thematic and tonal move away from Abrahamson's earlier work. All three of his first pictures were rooted very specifically in an Irish milieu: the hard-drug demi-monde; the isolated midlands; middle-class Dublin. Though much of the new film takes place in Ireland, its principal location can be found within the giant cranium of an eccentric rock musician on a mission to bemuse.

Domhnall Gleeson plays Jon, a young man who, almost by accident, gets drafted into an avant-garde band fronted by the mysterious Frank. An unpredictable, mentally troubled individual, the musician wears a large false head at all times. You must take it on trust one Michael Fassbender lurks beneath the comic prosthetic.

“We toyed with the idea of having a completely unknown actor,” Abrahamson explains. “But there aren’t many unknown and fantastically brilliant actors. Or, if there are, by definition we don’t know who they are. But the idea of getting somebody with a movie star face – a commodity – and then taking away that commodity felt thematically correct.”

It’s the sort of absurdist gag that Soronprfbs, Frank’s unpronounceable band, might appreciate.

“That’s right. But also, our Jon is a guy who, like many, accentuates his attributes on social media. We liked the idea that, in contrast, we have this desirable quantity and we hide it.”

Frank has a complicated history. Co-written by Jon Ronson, the story has distant roots in that journalist's time playing with the faux-naïve musician Frank Sidebottom. The Mancunian oddball, a creation of the late Chris Sievey, did, indeed, wear a head similar to the one in the film. All involved with Frank are, however, keen to stress that their work is, in no sense, "about" Frank Sidebottom. The character is American. The music is less cosy. The story veers in entirely invented directions.

“Jon Ronson told Chris Sievey that they were thinking of making a film,” Lenny explains. “They were interested in just sparking off this guy in the head and taking it off in these unexpected directions. And Chris didn’t want a film ‘about’ him. They were happy that they were making all this new stuff up. When the film was finished we took it up to Chris’s family and they were very happy with it. But there are die-hard fans that keep shouting: ‘Frank wasn’t American!’ There’s not much you can do.”

Well, I suppose they could have changed his appearance a little more.

“Look, to be fair, our character does wear a big head, he does play in a band and the film is written by Jon Ronson. The references are there. Celebrate that. It doesn’t stop people celebrating Frank.”

This is a rod that Abrahamson seems to keep manufacturing for his own metaphorical back. Two years ago, he had to discuss the loose connections between What Richard Did and the tragic death of Brian Murphy outside Anabel's nightclub in Dublin. When Room, the story of a woman and child imprisoned by a psychopath, is eventually released, he will be confronted with questions about the influence of the Fritzl case on Donoghue's novel.

“I know. It’s very strange,” he says. “I hope that, since Emma’s novel has been around for a while, the relationships between it and several other cases will have been worked through. That is now part of a finished conversation. That’s the hope, anyway.”

To be fair, those true stories are, indeed, constrained in the very deep background of Abrahamson's films and Donoghue's novel. But there is always an extra conversation to be had before he can get to the meat of the project. One assumes that it must have been a very different business promoting What Richard Did overseas. No glib accusations could be made that the film – concerning a much-loved student caught up in a violent death – was "capitalising" on the news story.

"That was different," he says. "Of the three films, it's the one that ended up making the biggest impression abroad – by far. Adam & Paul didn't travel so well initially because of the accents, though people do keep discovering it. I think it's maybe a purer viewing experience if you view it outside Ireland. Q and As abroad were purely about the film."

At any rate, What Richard Did scared up enough critical noise to allow Frank a relatively unimpeded path towards production.

Dear heavens, this is an agreeably odd film. After Jon is drawn in as keyboard player, Soronprfbs retreat to rural Ireland to record their masterwork. They play toothbrushes. They employ Dadaist randomising techniques. A Theremin is introduced. Fans of Captain Beefheart will recall stories of the great man's tyrannically odd behaviour during the recording of Trout Mask Replica. But there's also a sweetness to Frank. Fassbender really has constructed a performance of great nuance and complexity.

"We had obviously thought greatly about who could be Frank," Abrahamson says. "The danger was that you would end up with a fey central character, somebody with that wide-eyed Michael Jackson thing. But there's no way Fassbender would play it that way. You do get a comedic innocence, but you also have this sense of the Beefheart-like whip-cracking."

The film sounds like a bit of a gamble. But so far it has paid off nicely for the team. The premiere at the Sundance Festival drew raves. A later screening at South by Southwest in Austin, Texas went equally well.

“It’s an extraordinary offer to people,” he says. “But I think it’s my most conventional film. It’s certainly my most commercial film. We are largely happy. About 80 per cent of the reviews were really positive. The people who like it really like it. The rest don’t get it at all. That’s quite good. It’s a strong flavour. It’s not another bland film in the gloop.”

Rather neatly, the picture emerges a decade after Adam & Paul. By 2004, Abrahamson, a frantically articulate Dubliner from a Jewish background, had already established a reputation in the world of advertising. A full 14 years before that, shortly after graduating from Trinity College Dublin, he had made some noise with an excellent short entitled 3 Joes. A brief spell at Stanford researching a PhD in philosophy followed, before, in what then seemed like a slightly lunatic move, he returned home to make movies.

"I watched Adam & Paul for for the first time in seven or eight years recently and I really enjoyed it," he says. "There are these emotional resonances that result from it being a first film. It is still the film people know best. If I get a taxi and they ask me what I do they all know Adam & Paul. Kids on the street know it. It's a cult film."

As Abrahamson moves on in new directions – Room is being made in the US – those first films now look to form a neat anthology. Indeed, an academic of my acquaintance recently, talking rapidly as if the phrase was common parlance, described the films as "Lenny Abrahamson's Celtic Tiger Trilogy". This does make a kind of sense. Adam & Paul examines those left behind during the boom years. What Richard Did studies those who survived the crash. Garage goes among those living outside the financial conflagrations.

“Were they maybe the wrong way round?” he says. “No, that was a complete accident anyway. It’s very easy to retrospectively impose a narrative on these things.”

There are lessons for the Irish Film Industry in Abrahamson’s success. For those of us who remember him as a hairy youth, it is sobering to realise that he is, for many young film-makers, now something of a senior figure. One can think of few better men for the job. In my experience, Great Uncle Lenny is never afraid to express his opinions.

“Oh, what should I say?” he asks, pulling on a mischievous grin. “There is a lot of nonsense written about the poor quality of Irish film in one or two papers. Most of it is not good, but that’s true of all cinema. We only see the Danish films that make it outside the country. We see all Irish films. So of course we’re going to be more aware.”

He’s getting some momentum going. Where are we going with this?

“Having said that, we should be harder on the films we make. Critically, that’s changed a bit. We should also be tougher in how we make them. I don’t think enough work is done on scripts. I think we probably make too many films. I think it should be harder to get one made.”

Abrahamson will admit that it’s something of a luxury to be able to have this conversation. When he started out, Irish features were as rare as Irish spaceships. His generation helped turn an ambition into an industry.

“It used to like be Bear Grylls trying to get a fire going,” he laughs. “If there was a spark everyone would huddle round in case the wind blew it out. We can be tougher now.”