It's 2.30 in the afternoon, and on one of four or five studio soundstages, JJ72 are blazing through a live version of 'Snow', watched intently by dozens of techs, a handful of pop stars, and your reporter. It sounds pretty powerful for TV, Mark Greaney's evil choirboy voice soaring out over the sonic tsunami brewed up by himself and his bandmates Hilary Woods (bass guitar, evening gown) and Fergal Mathews (drums, bullshit detector).

TOTP, maybe more than most music TV programmes, is a great barometer of pop democracy, and this week hosts a fair fight between rock 'n' roll and bubblegum. Mere moments from now, Craig David and his polo-necked, black leathercoated Mafia will stride in and soundcheck their own appearance (and whatever about the music, the boy can sing). Ash have already run through their top ten hit 'Shining Light', and Tim Wheeler ambles about clutching a cup of coffee, marvelling over Bono's singing at the previous night's U2 Astoria show and grinning proudly when I mention the recent Westlife CD bonfire publicity stunt.

Then, on the other side of the coin, what's left of Atomic Kitten are perched on stools on a floodlit riser, bundled up in jumpers and running through 'Whole Again', their latest slice of pop-gospel, and a number one to boot. Later on, James Dean Bradfield of the Manic Street Preachers will proffer his bone-crunching handshake and profess himself both frazzled from promo duties for the forthcoming Know Your Enemy album and nervous at the prospect of playing two new tunes live. Jane Middlemass, her of the thick Geordie accent and NY Dolls chewing gum ad voiceover, pads by with her hair in curlers, looking like a cross between the Medusa and Hilda Ogden.

As you'd imagine, there are connections aplenty. Not only do JJ72 share management with the Manics, but also Mark and Fergal have been bonding with their respective opposites in the U2 camp, in town for the last week or so. On top of that, I run into Mark's guitar roadie Acko, whom I've known for 17 years. Chatting in the canteen about U2's lockdown TOTP appearance the week before, I learn that the band's backline set up is so sophisticated, Edge can dally until the last minute before deciding whether to play live guitar or mime, while Bono's an old TV pro, issuing instructions on camera angles to the crew.

Forgive this most obvious of parallels, but JJ72's trajectory frequently emulates and sometimes outstrips the U2 pilgrims' progress in London exactly 20 years ago. Mark Greaney accepts the comparison without complaint, probably because he wants the low-down on the previous night's Astoria show, which the JJ entourage missed due to overrunning TV rehearsals, although they had hooked up two days previously at the NME Brats awards in the same venue.

"It was cool, I ended up talking to Bono for an hour about things you'd talk about to other people who are into songs," he says. "And it wasn't like, 'Hey, I'm talking to a megastar so I better be cool', we just started talking about pop songs in general. And it was so weird, we were sitting at the table after the main awards were over, and there were loads of people walking by, just constantly looking. Talking to him like that the other night, out of all the people we were talking to, the amount of real bullshitters, maybe I'm just naive about it, but a lot of the things we were saying to each other about pop music were the same things. And Fergal was getting on really well with Larry Mullen talking about bikes, Larry trying on his jacket, drummer talk. It was good."

How does Mark feel about Bono namedropping the band in interviews?

"It can be a bit weird," he concedes, "like the Manics have said it as well, but it's down to the way people interpret it. Bono was apologising for mentioning our name in interviews, and I was just going, 'this is so surreal. I'm sitting at a table with Bono and he's apologising for complementing me'. But it's also like, there aren't really any Irish rock bands who've done anything in a while, so while it's not an easy option, it would be kind of obvious to namecheck us."

Some might take such statements as arrogant. Maybe they are, if you define arrogance as a lack of false modesty. For what it's worth, I think JJ72 have made a solid debut album and a clutch of good-to-great singles, but the things that impress most about their organisation are chiefly non-musical. For instance, they're obviously smart, well-mannered (and if that sounds a bit Jane Austen, good grace goes a hell of along way on a tour bus), and extremely self-critical and pragmatic about where they need to go with the next record.

"A lot of people, especially British press, see that as careerism," Mark points out. "(But) as a journalist even, it's not as if you don't dream to write for someone else. It's the same with everyone, it doesn't just stop at a certain level and go, 'Oh, whatever happens, happens'. It's just a real indie mentality if you're not allowed to think of where you could be going. There's so many British bands, I've met them already, who so believe what they're told by the NME or by other English bands who are at the same level as them."

The recent Brats awards served as a kind of graduation party for the band - this their third TOTP appearance, the album's gone gold, and they seem well on the way to breaking out of the indie ghetto and into the Q world of mainstream acceptance, a situation bound to be reinforced by forthcoming tours of Scandinavia, the US and Japan. Plus, they get followed around while shopping in Manchester.

"When we started the band, of course the idea was to sell 10 million of our first album," the singer admits, "not because it was 10 million albums, but because a band like Nirvana did something similar. It's the ideal behind it as opposed to the actual figures. Obviously that hasn't happened, I realised that wasn't gonna happen when we made the album, and you're probably not gonna believe me, but I'm glad that it's not 10 million people, because there's no pressure."

Okay, so much for the Manicsfesto. But what kind of music were the band weaned on?

"The trigger to start a band was Nevermind, that was the ultimate pop-rock album, but I think things have snuck in there I only realise now in retrospect- classical music, I played the violin from about six. Certain sounds do stem from this basis that you can't remember properly, records my parents played. My mum was into Spanish guitar, mix that with a bit of Rod Stewart from my dad (laughs) and Roy Orbison."

The Big O - I thought so. Many of the songs off JJ72 ('Undercover Angel', 'Oxygen') remind me not so much of Boy or Mellon Collie or In Utero or 17 Seconds or Unknown Pleasures so much as Nick Kent's description of songs like Orbison's 'Running Scared' as "a very heightened expression of a very adolescent state of mind". Either that or Portrait Of The Artist As A Young Man transposed into the archetypal power trio format.

"Definitely," Mark concedes. "It's difficult to talk about a song like 'Pretty Woman' without thinking of Julia Roberts, but if you take the simple idea of what a song like that is about, a moment where he sees a bird walking down the street, you don't have to be 16... even the stuff you mentioned, James Joyce, you take parts of Dubliners, where there are little moments that are mundane on the surface, but when you actually read them, you realise that that could quite possibly have been an epiphanal moment in someone's life."

Which of course, was also Beckett's speciality. "Yeah, it's those little things... realistically, the thing to write about is the mundane, because, I know it's paradoxical, but they can be the most vivid things that'll ever stand out in your memory. And that's what the first album is about. Okay, I did it on a very simplistic level, but there's things like, every fuckin' review I've seen of the single 'Snow', I'm getting a little bit fed up of: 'Oh, I think someone should talk to Mark Greaney about the weather-we have had some of the white stuff so far this year'. I'm not saying it's an extremely complex record, but that song is not just about snow obviously! C'mon, please, gimme a little more credit."

"Maybe I didn't do it very well," he considers, "that's why I feel so ambitious with this next album. I think a lot of listeners, kids who are 16 or whatever, have listened to the record and are intensely devoted to us because they can pick up on those little bits clearly, they've a better radar sense than, no offence, NMEjournalists or whatever. People take the piss 'cos it's teenage angst, I dunno, maybe it is, but I wrote a lot of those lyrics during summer exams. I was meant to be doing my Irish essay and I'd be doing the lyrics for 'Long Way South' or something, and that's where they came out of. I didn't sit down to write poetry, they're actually very stream of consciousness things."

Yet angst isn't the preserve of the teenaged. For the record, Mark and Fergal, like that other JJ, attended a Jesuit school, Belvedere College. When I bring this up, the singer expresses surprise that no-one's copped on to elements of Joyce's 'The Dead' in the latest single. "My mum handed it to me when I was 14 or something, in hospital with my tonsils," he remembers. "And that part at the end of 'The Dead'... maybe it's just a coincidence, but also Oscar Wilde's children's stories for some reason, since I was 12 I used to read them all the time. There's little things that you almost want to keep to yourself because you don't want them to steal the magic, the purity, whatever, and that's why the songs on the first album, they stem from places which can be looked upon as pretentious with a capital 'P', but they stem from it in a very simple, very innocent way."

One frivolous but nonetheless notable benchmark in JJ72's ascension from indie-rock status to serious middleweight contenders was bassist Hilary being voted sexiest female rock star in a Melody Maker poll published shortly before the paper's demise last year. This is a tricky one - it's funny how beauty sometimes gets treated like a dirty little secret. In person as much as on the cover of magazines, there's no denying that the JJ bassist has an achingly pretty face, but it could be argued that such attention does her a disservice as a musician.

Mark: "Music magazines pigeonhole everything, but when they start doing it with bits and pieces of people's personalities it's annoying: 'So Mark, are you the Hitler of the band and are you annoyed because Hilary is getting attention?' I'm not saying you're asking me in the same way, but I think music is still the one place where a male can treat a female like an absolute and utter piece of meat, and that's what so many journalists have done, straight to Hilary's face, asking her about her cheekbones. It does get annoying because if it annoys Hilary it annoys the rest of the band. But having said that, it's very difficult to complain about it, because once you release a record and allow yourselves to be photographed for something, the other side of the argument is, well, you're asking for it."

But also, to complicate matters, there's the fact that Mark asked Hilary to join - and in fact, taught her how to play - not just because she loved Smashing Pumpkins but because she looked much cooler than the band's first bass player. "To be honest, y'know, myself and Fergal were big into Sonic Youth and the Pumpkins," he admits, "and part of the appeal was we fancied the arse off D'arcy from the Pumpkins when we were 16. But what we didn't realise at the time and we do now, is the fact that what's appealing about bands like that is it doesn't have to be five guys who went to college together getting pissed up every night in the student's bar and then they go in and start writing Oasis covers.

"And I'm gonna be sexist now and say it, but there's a huge difference in dynamic when you've got a female in your band because things are more intense, things are a lot more fragile or open. Maybe it's not like that with every female, because I'm sure there are complete tomboys, but it's the way it is between the three of us and it's the essential element of the band. People just dismiss Hillary as the good looking one in the band but for us to get on stage and play certain shows - and I'm gonna use a cliche here - it is about chemistry between three people."

Later in the day, in the band's dressing room, I ask Hilary how she feels about being a pin up for the raincoat brigade. "A raincoat pin-up?" she laughs. "That's kind of to be expected in the world of Melody Maker. A lot of bands are talked about in that light. People that are really into the band see beyond that - it would be incredibly sad if they were into the band because I was voted in some poll. At the same time it was quite flattering. It was funny." Perhaps so, but one gets the impression that Hilary is as self-conscious as any 20-year-old thrust blinking into the spotlight. Talking about inadvertently smiling while getting drenched with water in the 'October Swimmer' video, she says this: "I wasn't meant to smile - I don't like showing my teeth."

No wonder all the little goth boys are swooning. Speaking of videos though, one thing I must confront Mark about is the wanton smashing of equipment in the 'Oxygen' clip and at various live shows, a gesture this writer has always considered to be the most hackneyed of rock 'n' roll rituals, a hollow consumerist parody of teenage rage. It may have had an impact when Pete Townsend did 35 years ago, but has lost all meaning by now. Endearingly, the singer almost blushes. "You're not gonna believe me when I say this," he responds, "but we did a London gig the other night at the end of the NME awards, and okay, we trashed the stage not because we think we're maaaaad, but because it's just actually such good fun, pure and simple. I know that's not much of an excuse, but there are kids in the audience who go, 'is he gonna smash his guitar tonight? Yes, he is! Yes!' And sometimes the biggest cheer can be when I snap the guitar, and that is a buzz. I'm not gonna say that anyone in the band is without some sort of ego, 'cos when you hear that extra lift in volume from the crowd, you do get an extra tingle. So maybe it's not the actual process of smashing something any more, but when you realise you can turn other people on..."

Do you only smash cheap copies? "Yes. Acko's developed a very good thing of - I shouldn't be telling you this - but he puts superb Humbucker pick-ups into cheap copies, so the Humbucker is worth more than the actual guitar I break, but it always goes flying through the air and lands on the stage safely. So we're just complete accountants, JJ72! I've only started to realise the actual thing of 'doing' a stage is really good fun for me. I know you obviously avidly hate it, but myself and Fergal were in my house ages ago and we saw footage of Nirvana playing some really old gig and Kurt broke his arm or something jumping into the kit. "It's the idea behind stuff like that, it's not cutting yourself open. We were trying to ape in some way what we saw Nirvana do, but when you try and ape something, it can sometimes run a lot deeper than just the actual act of doing it. I'm trying to describe one of the main things that drives us playing live gigs, that makes us feel on a different planet. It's kind of when you do lose control slightly and are prepared to do pretty much anything at that moment in time."

So, JJ72, a band from Dublin but not of it. Over the last year the trio have been battling the misconception that they have some kind of a problem with their city of origin. It's a myth they're anxious to dispel before the forthcoming Olympia gig, and this Hotpress piece obviously means a lot - throughout the day, I count at least half a dozen occasions when members of band, crew, management and record company ask me if this is to be a cover story. As Hilary explains, "the cover of the NME means nothing to my granny."

Still, the band opted for exile in the Kingdom, bypassing Temple Bar tiddlywinks. "We just went, 'We're outta here for the time being'," Mark explains, "not because we don't like Dublin or the people, but because there's a tiny amount of people within the music scene who we, to be honest, could not be arsed with, and those people are still there. But the fact is I've no problem with Dublin or Ireland as a whole, because in relation to Britain there's the same amount of people who love our album and went out and bought it."

I put it to Mark that perhaps JJ72 were seen as emblematic of the new breed of young Irelander living on an assumed sense of privilege which rankles the hell out of pauperised pre-menopausal meanies like myself. "It would make sense in one way," he concedes, "because to be honest, it's nice to know we've created something ourselves in the last year, we can actually live off what we're doing, and that's strange to happen to you when you're 20. And maybe over the last few weeks it's getting stranger because we're selling 10,000 albums a week in Britain, and the result of that is a lot more attention. Fact is, when I go home, even my parents are a little bit more wary of who I am." Hilary: "Last time I was in Dublin I was just getting my hair chopped and the hairdressers knew what band I was from, and they presumed we'd gotten so far because of managers, it was nothing to do with the band, and some people misinterpret that because of sensationalism."

Mark: "People can say I sing like a dog getting choked by its bollocks or whatever, that's fine, I don't care, 'cos anyone has every right to hate what we do. But the whole idea of going home and people treating you different is a little bit weird, slightly uncomfortable. But having said that, I don't think I'd want it any other way at this moment in time."

Silence, exile and cunning, those are the three attributes Joyce reckoned any Irish artist needed to survive the mother country. JJ72 possess the last two of those criteria, and maybe that's enough for now - silence is overrated.

"The reason I can go and do Top Of The Pops today and actually be brimming with confidence doing it is because I know there's something a lot more special to come along," Mark concludes. "Maybe my cynicism has grown over the past year or something, but that line is there between people I would've elevated to some kind of god-like status before, and the actual reality, which is that we gotta create things ourselves which are powerful."

And as night encroaches, and the fans start filing in through the front gates, JJ72 get ready to run through their latest single one more time for the cameras. Dressed in a baggy grandad shirt, with hair askew, Mark begins to sing...

"People go dancing in crowded rooms, My head is getting tired, darkness looms"

...and you figure they should run Joyce on the autocue:

"His soul swooned as he heard the snow falling faintly through the universe and faintly falling, like the descent of their last end, upon all the living and the dead."