Stuart Carolan has been up much of the night with a crying baby (his third child with Emma Kelly, owner of Elevate PR) and an unyielding script (he has a few on the go). "I haven't had much sleep," admits the writer of RTE's remarkably good drama, Love/Hate. Maybe this is why when he occasionally says, "Let me think about that for a minute," he literally thinks in silence for a minute. But he's very well-informed, with a ridiculously good memory for Irish current affairs and pointed quotations from other writers.

This might stem from his time as producer for Eamon Dunphy on The Last Word from 1997 to 2002. "I was always a current affairs junkie," he says. "And with The Last Word you could immerse yourself in that. You might read something interesting in an American newspaper and you could then go and get the guy and actually talk to him. Without being the producer of The Last Word, I'd just have been a nutter ringing up for a chat. I can't remember a lot of things about that period to be honest with you... I was living in the moment. But it was great. I was fairly young and worked very hard and Eamon Dunphy was a great mentor."

Dunphy has a reputation for being erratic and difficult to work with, I note. "Not at all," says Carolan. "I'm a bit erratic myself, maybe, but I found him fantastic. He's fearless. He has a great mind and he doesn't take himself too seriously. I try and meet him for lunch every so often and have a great time."

Dunphy possibly unwittingly gave Carolan the writing bug by encouraging the creation of the satirical mainstay of the show, Navan Man, a character Carolan voiced and wrote with great success for several years. Five years later however, Carolan left "on a whim".

"I remember being on a Ryanair flight and it was August and I was thinking about what we would be doing in the show. In August there's no news agenda as such and it's a terrible time to be a journalist, and the flight was a bit bumpy and I was thinking 'what if it crashes? What would I like to have done?' and I thought 'I'd love to write just one play... just one'. It was as simple as that. I rang Eamon when I got back."

There's a bit more to the story. "I was also in contract negotiations and they didn't want to pay me any more money. Now that wasn't the reason, but when you look for more money and someone says 'no' you have to really want to stay. And I didn't at that stage."

This wasn't quite the end of his career in media. "I met Eamon for lunch and we were bitching about The Late Late Show, and some­how we decided to launch a rival show. So we did The Dunphy Show. It didn't work," he says, and laughs at the understatement. "You felt the might of RTÉ up against you. They put Celebrity Farm up against us and they even changed the slot of Prime Time so it would be on a Friday. We thought we'd get better ratings." He pauses. "We didn't." The Dunphy Show was axed after 12 of its mooted 30 episodes.

By then Carolan was firmly ensconced in the world of fiction. His first play, Defender of the Faith, set in south Armagh at the height of the Troubles, was put on in the Peacock that spring, and another, Empress of India, a black comedy about grief, was produced by Druid two years later. He also dabbled in television, writing the romantic comedy Little White Lie with the comedian Barry Murphy, and he wrote an episode of RTE's literal kitchen sink drama, Raw.

"You know that Malcolm Gladwell book where he says you have to put 10,000 hours into something to be truly good at it?" he asks. "Well, I've put in about 20,000 into writing. I've written a novel which was never published. I did a screenplay for Defender of the Faith with Noel Pearson but it never came through. And I did a six-part comedy series with Barry Murphy for RTE that never got made. That's very dispiriting."

And through this process he got a very clear idea of how he wanted to write. "I learned that in television writers are often treated like nobodies. Your opinions just aren't canvassed. In America, with a lot of the successful shows the writers are producer-types who work closely with the directors. But often here the process involves having two script development people going between the writer and the director and a lot gets lost."

Over the course of our conversation Carolan often goes into forensic detail about the programmes that fascinate him and he does so here. "There's an episode of The Sopranos where Tony has had Adriana [his nephew's girlfriend] killed because she's been informing," he says, leaning forward in his chair. "And at the end of the episode Carmela [Tony's wife] is talking about not getting planning permission for this little house she's got, and Tony has just heard that Adriana is dead. There's no dialogue apart from Carmela wittering on about planning permission, but you can see a look on Tony's face that's a mixture of disgust, because Adriana was like a niece to him, and relief that he won't have to spend 30 years in prison, and also mild annoyance that his wife is talking about something so banal. And at no stage is there any dialogue apart from Carmela's discussion of planning permission. It's amazing."

Carolan realised that in order to make television drama like this, he would need a collaborator who would allow him to be more hands-on in the production process. He found this in director David Caffrey. "We'd met on Raw and there was great chemistry there. We worked together from a very early stage of the script of Love/Hate. At the scripting stage I was the boss but he could suggest anything. Then once he started shooting, he was the boss and I was making all sorts of suggestions." He laughs. "He mostly listened." As well as praising Caffrey, Carolan also makes special mention of Donal Gilligan, Love/Hate's director of photography, who died tragically and unexpectedly two weeks ago ("He's largely why it looks so good").

Why did he want to write about this stuff in the first place? What was the appeal of 'gangland'? "I wondered 'how to explore hate and love?' How do you do 'love' without being too sentimental? How do you do 'hate' without completely alienating your audience?"

The way he did it was by trying to present the real and nuanced lives and loves of a gang of drug-dealers. He did journalistic levels of research on the topic, but unlike many crime reporters, he resisted the urge to judge. "I've a natural sympathy for the victims, of course. And I'd hear stories about individuals from gangland and the deeply unsavoury things they'd done and I'd think 'maybe it's a good thing they've been shot'. But I also felt all sorts of other emotions about these guys – sympathy, anger, indifference... everything."

So you weren't trying to make any particular point about gangland? "No, I want the audience to feel confusion about their emotions. People have murderous rages in them and gangland is just one aspect of it. There's a rage in society. That guy driving his truck into the Dáil... or Charlie Haughey's line in that interview with John Waters years ago: 'I could instance a load of f***ers whose throats I'd cut...' That rage is always there."

He seems to be arguing that Love/Hate isn't really about gangland at all, that it's about human nature and, maybe, wider society. "It's a drama. The main thing is to tell the story in a dramatic way, but it's a little more complex than a simple 'shoot em up'. If you live in society you're affected by everything in it." He pauses. "You know when John Gilligan said he'd made all his money through gambling and it was called 'the Gilligan defence' and then Bertie used the same excuse in the tribunal. Bertie used the Gilligan defence. I thought of using that as a line but it just felt crowbarred and hackneyed. I am aware of the links between different things but you want to be cautious and not be libelling left, right and centre."

He goes on, strictly off the record, to tell a story involving another public figure which is totally unrepeatable. Is this why he moved from journalism into fiction, to tell the stories which can't be told (yet)?

"Maybe," he says. "But if you approach it with a sense of moral superiority it doesn't work, I think. I certainly don't feel like 'a righteous man'. Some days I feel rage and savage indignation, but I write best if I think like my characters and there are 15 or so major characters in this who think in different ways. I think if you feel moral superiority as a writer... well, you might as well be writing poems about tractors in Stalin's Russia."