Danny Boyle says being a director is boring 95per cent of the time. "People don't realise this, " the man who made Trainspotting, 28 Days Later, The Beach and now Slumdog Millionaire is telling me in a clubroom in London where the decor is so painfully psychedelic that our eyes are strobing. "It's basically like a schoolteacher. Both of my sisters have been teachers - neither of them are teachers any more, they got worn out by it - but they used to say you get asked between 300 and 600 questions every day which you have to answer. That's exactly what directing is. And the vast majority of those questions are not very interesting questions, really, but they need somebody to make a decision, a good one or a bad one, and they follow it."

Even though Boyle, now 52, has been making good and bad decisions since the late eighties, through eight movies, a couple of television . lms and the odd episode of Inspector Morse, he's not feeling worn out yet. He's made big films and small films, directed superstars and wannabes (and turned some of the latter into the former along the way), made good films and maybe one or two not so good films. From my seat in the auditorium I'd say the good decisions outnumber the bad ones.

And Boyle has also made a couple of great . lms. It's possible his latest might be one of them. Slumdog Millionaire, written by Simon Beaufoy ( The Full Monty), is a helter-skelter whiplash of a movie set in the slums of Mumbai. It is bold, bravura, big-hearted, at times unashamedly sentimental . lm-making (with a Bollywood dance number after the . nal credits). It has the pace and the pathos of Trainspotting - although it's a much better movie - and a toilet scene that outgrosses Ewan McGregor's crawl into an ordure-. lled U-bend It's the most fun you'll have in the cinema this month. And, if pre-release hype is to be believed, it might even be in with a chance of an Oscar nomination. Quite something for a small-budget movie set in India with no recognisable faces to speak of that speaks in sub-titles and nearly went straight to DVD in the US when its distributor Warner Independent folded (Fox Searchlight stepped into the breach).

Talking about the making of it, Boyle doesn't sound bored, it should be said. He raves about the experience of filming in Mumbai, the speed and rush of the place. In doing so he could be almost be talking about himself. Words spill out of him pell-mell. He doesn't do one or two-word answers. He says he loved the challenge of . lming in the Indian city. Not everyone else did. "We took about 10 people and a few of them weren't really up for it. They wanna do the job because it's me and we have a relationship and they want to complete it because they're professionals, but they weren't really up for it like I was They couldn't wait to leave, whereas I loved it."

As you can tell from the . lm he's made, Boyle is in love with Mumbai in all its wealth and squalor, all its excess and indifference (when we speak, the terrorist atrocity that will kill 174 people is still to happen). "Simon has a great expression for Mumbai: 'It is moving in fast-forward'. And it is. You expect as a Brit that there'll be some recognition of you because, after all, we were there until 60 years ago. That's nothing really and we left a lot behind. But it's not there at all now. Simon was there 20 years ago and he says it was there but now it's not. We're only an anecdote, the British, because the city is fast-forwarding towards America, China, Russia. They're very, very competitive."

Making the movie, he says, he didn't want to show himself up as a tourist. "I was very wary of that whole 'oh India, look at that. Amazing'. I didn't want to do it like that. Cause I think you can get lost in that very easily. And they are very funny about it, the Indians. The crew'd say 'I bet you'll have a cow in it somewhere.' They take the p- really rotten. What they make of the . lms that are made there, you wouldn't want to pass on to some of the film-makers."

He laughs at this. The sound is a persistent, rhythmic "hur, hur, hur". The best description I can come up with for it is a Lancastrian drill. Not a little whiny dentist's cavity-puncher, but one of the big heavy ones that chew up concrete. It's just a hiccup in his answer, though. "Anyway, " he says, "I thought I'd try to get really subjective really early with it, so it begins in massive close-ups and then you hurtle into this chase through the slum and you're kind of like tumbled into it and it is a bit like that arriving there, you've no time to catch your breath. You can catch your breath in your five-star western hotel, but everywhere else it's full-on. It's coming at you all the time. You've got to be up for it."

Danny Boyle talks like he films. At speed.

Rewind to earlier this morning, the morning after the night before. Last night Slumdog Millionaire was the closing film of the London Film Festival and it went over big. When Boyle arrives he's tired but elated and desperate for a cup of tea. He chats away as he gets his photo taken in a room wallpapered in sylvan glade. The decor makes him think of a scene in a movie. David Bowie had a room like this one in The Man Who Fell to Earth, he recalls. Film is his language of choice.

One of the reasons I wanted to talk to him was something Pat Kane - media intellectual and singer with Hue and Cry - once said to me: "Teddy, you're an Ulster Protestant.

How can you love cinema? It's a Catholic medium." I reckon Boyle, who thought of training for the priesthood before joining the church of cinema, is the perfect person to ask if that is so.

"There's some truth in that, " he says. "I used to tell people this stuff about how I was meant to be a priest and they'd say, 'yeah, like Scorsese and John Woo. There's a strain of it in there and you can think it is very imagistic and ceremonial as well. I was an altar boy for years and years and years so there's a lot of that going on I guess, yeah."

Well, is cinema for him now a substitute for religion? "It's certainly something ?" He pauses. "I abandoned religion as soon as I got into my teens. Viciously. As viciously as I could without destroying my mother. Obviously what comes in, in its stead, is culture." By that he means music and movies.

Boyle grew up in Radcliffe, a small town between Bury and Bolton the oldest in the family. "I'm a twin and I'm the elder twin. That was my sister on the phone earlier when I was walking in. And I have a younger sister as well." He had, he says, a "fantastic upbringing" in a traditional family set-up. "It was pretty patriarchal. You're the boy who's allowed to do anything really, whilst the girls have to get sensible jobs. My dad was a labourer, my mum had exactly the same job as Noel Gallagher's mum, actually. She was a dinner lady at our local school. Everyone comes over from Ireland and they get the same jobs."

His father was labouring from the age of 12 to support his family because his own father had died. A world away from Boyle's experience. "I've sort of escaped my background as people often do through art and culture. I've managed to get away from the town and I see my mates who are still there and it's weird."

Boyle passed his 11 plus, went to a grammar school and then to university, "not a very good university. Had a great time, did drama and English, got into acting and discovered directing." He got a job driving a truck for a theatre company in London and worked his way up. "People are always desperate to know how to get into the industry. It looks impossible and it is impossible, but if you persist you'll always do it. If you're mad enough for it. And then once you're in and if you've got any talent it will get sought out. Because it's all about that really."

Perhaps that's the optimism of the successful talking there. Then again, as he says, people complain about how dif. cult it is to get into the movies now - how far away did it seem to the teenage Boyle working at Bolton Octagon as an usher? "F- hell, then it felt like a completely alien word that you'd never get into."

After working as a director in the theatre, though, he applied for a drama producer's job with BBC Northern Ireland in the 1980s. "Nobody wanted the job because it was a tough time in Belfast and over here people didn't know anything about Belfast. It just looked frightening. But I'd been there loads of times and it's not frightening at all. Quite the reverse, actually.

"Supposedly I was the only applicant from outside the region and they weren't going to appoint inside the region for their own reasons - political, religious, all that - so they appointed me. It's much easier to bring in an outsider, an Englishman, a Brit."

When he arrived Boyle told his new employers that not only would he be producing films, he'd be directing them as well. The fact he said he'd only take one fee swayed them. Soon he moved on to episodes of Inspector Morse and a drama series, Mr Wroe's Virgins. Then he got the gig to direct the . lm Shallow Grave. And things took off.

For a while he was part of a golden team, alongside writer John Hodge, producer Andrew Macdonald and star Ewan McGregor. They all got on well but were never best buddies, he says now. "We didn't mix socially, but we brought different things to it and that's what you need to do. The danger with being a director, especially one with a bit of a reputation, is that people become passive. 'Yes, you're right.' And sometimes you're not. It's better when people are not frightened to say what they think. We really began as equals."

After Shallow Grave the quartet hit paydirt with the big-screen version of Trainspotting. The night before we speak Bollywood star Anil Kapoor had told a Bafta audience the reason he signed up for Slumdog Millionaire was the adaptation of Irvine Welsh's novel. Somewhere in India, it seems Begbie, Renton, Diane, Spud and Sick Boy, in all their two. ngered, shaven-headed, big-specced, drugfuelled Scottishness stare down from Kapoor's teenage son's bedroom wall. A teenage son who told his dad he had to make this new movie because it's a Danny Boyle movie.

The director John Boorman, another English visionary, once said filmmaking was all about "making money into light". But the light also has to make money. How does it feel, I ask Boyle, when one of your . lms - something like The Beach, say - is unsuccessful?

Well, he tells me, it wasn't. "The Beach was hugely successful. The Beach has made twice as much money as any other . lm I've ever made. I know why people say that, because of people's opinion of the . lm. But actually you have to look at the . gures as well. That . lm took dollars150m around the world. I think maybe 28 Days Later took half of that. Trainspotting maybe took half of that. It wasn't a big flop at all. It's to do with Leo. If we'd made a really successful . lm it would have made billions because he was so successful at the time. That's why people think it's a flop, because the value we got out of Leo was minimal compared to what the potential was to make money."

He didn't enjoy the shoot much, it should be said. The reasons he gives have nothing to do with the fall-out with McGregor (who thought he had the DiCaprio part) or accusations that . lming was destroying paradise. No, he says, he just didn't like the movie much.

"I'm an urban person. I love cities and I made that . lm about a load of hippies in the countryside, nothing in common with them at all. You're there making the . lm and you think, 'I can't relate to these people at all. What the f- are they doing here? I am so bored."

He once told a tabloid that the shoot was all about "girls, girls, girls, money, money, money, drugs, drugs, drugs." Which of those temptations did he succumb to? "I didn't, really. I was not a happy bunny on it. A lot of my crew had a good time." He changes tack suddenly. "The story that journalists want to use is that Leo was a c-, and he wasn't actually. He's a fantastic guy. He's desperate. He wants to have a big relationship with a director. He uses his power to bat away the studio. He would say to me, 'do you want to shoot that . ve-day sequence again? We can do it again if you want?' That's what he uses his power for. He has very European taste. He wants to smuggle European art . lms into the American market."

Boyle's problem with making the movie, he says, was he didn't know why he was making the movie. "I don't like these people very much and I don't approve of what they're doing so we tried to make the . lm critical. But of course, you've taken dollars55m. You can't make a sociocritique of these invaders for dollars55m. If you take dollars15m you can, but you've taken dollars55m so there's got to be a romance and it needs to feel like paradise. It needs to sell itself like that."

The money spent on movies is, he says, obscene. It's something his background couldn't have prepared him for. "I remember ringing up my dad when I got this Inspector Morse job. I'd never been paid so much money in my life. And they were limited jobs three months' work. It was very good, but it was a factory none the less. You joined, you made it, edited it quick, left. But they paid. That's one of the reasons they were so good . I remember ringing up my dad telling him how much I was going to get paid and I realise now it was very insulting to him because it was more money than he ever earned. You always feel guilty about it. But I think that's healthy, because it's an obscene world we operate in sometimes."

It's an issue for Boyle, obviously, because he operates in a world that works in seven and eight-figure sums. "I feel very self-conscious about money. To handle a big amount of it you have to have an abandon. You can't feel guilty about dollars100m. You just have to think 'f- it, let's just spend it like this'. I don't like people getting cars everywhere and that side of it. I prefer to get it and spend it on the screen if you can."

This issue of money and the notion of success are things that obviously nag at him. We return to both a few moments later. He has been talking about his life away from the . lm set. He lives in London. His three children live up the street with their mum. "We split up many years ago but we remain good friends." If he's sacri. ced anything he says it's time with the kids. Now he lives quite a solitary life and he likes that. "People think I'm lonely. I'm fine, I listen to music and read and I watch the telly, pretty boring stuff like that. You're not in a nine-to-five job. You get a few weeks off suddenly. I've learned not to feel guilty about a couple of weeks off now and then."

If you want to know about Boyle's character you can probably read a lot into the requirement to learn not to feel guilty. His workingclass work ethic is, he says, "stained" into him. But he's not quite . nished worrying away at the topic yet. "It's not so much guilt as embarrassment at any kind of success, " he continues. "So you don't really enjoy success in a way. When we had a big success with Trainspotting and with 28 Days Later I did not - as you're meant to do - party hard. You look back on it after you've had a few fl ops and you think 'f-, I wish I'd partied hard'. But when you have a big hit it doesn't really work like that. I'm not really like that."

What is he most proud of? "What? In the films or in life?" Both. "Well, the kids are amazing. The films ? yeah, I've got to be careful of overvaluing them." Maybe not a substitute for religion after all, then.

What would you learn about Danny Boyle if you watched his . lms? That he is cynical, he says, has a black sense of humour and is also sentimental. He hopes you'll see the tenderness in them. That's the key. Beneath the heat and hustle of his films there's a heart.