WHISPER it. Snow Patrol have become Ireland's hottest band by a Bangor mile. Last week, their fourth album, Eyes Open, officially became the biggest selling album in Britain during 2006. In September, their single 'Chasing Cars' was the number one downloaded song on iTunes in the US while in Ireland Eyes Open debuted at No 1 and has resided in the top 20 ever since.

They have supported U2, played the David Letterman show and this month were nominated for a US Grammy for their mega-anthem 'Chasing Cars'. A bloody Grammyf But don't tell Gary Lightbody that his band is breaking the US.

He's not interested. "We are perhaps not selling as many records there as some people might think, " he says diffidently ahead of the band's homecoming gigs this week.

Modest and unassuming, the two Scots and three Irishmen are pop nerds, obsessive in their love of a romantic melody and their disdain for the cliche of rock stardom. They don't go out with supermodels, Lightbody reportedly doesn't drink alcohol during tour and they don't even wear funny clothes like Coldplay.

Snow Patrol are you and me.

That's why the prospect of hanging out with the stars at the Grammy ceremony next February does little to excite the 30-year-old Lightbody. "I don't know if we'll be going, " he says somewhat surprisingly. "Award ceremonies are not really our cup of tea. It would be very embarrassing walking along the red carpet and all the photographers wondering who the hell we are. No one even knows what we look like. It would be quite stressful and not enjoyable."

So who the hell are Snow Patrol anyway? It's over 10 years since the Belfast-born, Campbell College-educated Lightbody and keyboardist Mark McClelland went to university in Dundee and started gigging with a variety of musicians that included Belle & Sebastian's Stuart Murdoch and Richard Colburn. They were then known as Shrug, later Polarbear and then, after the threat of legal action over that name, Snow Patrol. They signed a deal with cool indie label Jeepster, moved to Glasgow and recorded a couple of rock 'n' roll albums. In came big record label Polydor, a new guitarist in Nathan Connolly (also from Belfast) and an album called Final Straw which featured their first big hit, 'Run'. Both album and song went top five in Britain and starting making a splash worldwide. The band kept touring, building up a dedicated fanbase and a low-profile image.

The critics didn't think they were cool and neither did they.

"We are completely ordinary people, " says Lightbody, sounding like he doesn't know what all the fuss is about, "but the sum of our parts is valued at a hell of a lot more than the individuals. We are very proud of our music but as people we are pretty dullf I think deep down [anonymity] is something every band desires. I can't think of one reason why you would want to be famous."

Final Straw has sold almost two million copies since its release in 2004, around the same as Damien Rice's O album.

Not even a year old, Eyes Open has already surpassed that total.

"Because we toured so much, Final Straw did well but this time with Eyes Open we coupled that with having a really big radio hit and we weren't expecting it, " he says.

'Chasing Cars' was an unexpected hit in many ways. A slow-burner even for a torch song, "it seemed to connect with people and took on a life of its own".

While Lightbody is not quite resentful of his new-found fame, he clearly sees its negative side.

"People might hear that song and only that song and see us as just that, " he says. It's his way, one suspects, of explaining how the band have become one of the longest overnight success stories around.

Key to such mainstream acceptance is Lightbody's ability to pen perfectly vulnerable lyrics of broken-down relationships and set them to triumphant, sweeping anthemic chord progressions. The music is all about shared experience.

Currently unattached, he attributes his ability to deal with commercial success and all its traps to a myriad of humbling experiences in his love life. "If we had had a hit earlier in our career my ego would have gone super nova, " he laughs. "But my ego has been dragged along the back of a wedding car like a bunch of tin cans for the past couple of years. As it is, it now resembles a chicken leg with all the meat eaten off itf" Such honesty and humour certainly strike a chord with listeners and the irony inherent in the band's elevated status from humble origins is not lost on him. "It's a paradox that our success comes because of our sheer ordinariness, " he deadpans.

One notable casualty of their success was McClelland, who was fired from the band in early 2005. Lightbody still clearly misses his old friend, even if a line has been firmly drawn under the whole episode.

McClelland's replacement, Paul Wilson, "slotted in wonderfully but it was hard because Mark and myself had been writing music together for over a decadef" The success of 'Run' meant Snow Patrol had earned themselves another chance at the big time. They went down to a cottage in Kerry (that Kate Bush had once used) and grasped it. Eyes Open was recorded during 2005, the year they supported U2 and played Live 8 both in London and Scotland. By now Lightbody was becoming more vocal in his political and charitable convictions. A member of Amnesty, he recently jumped at the chance of recording a song with Lisa Hannigan for The Cake Sale's album for Oxfam Ireland.

And when Eyes Open was embraced by America, Lightbody became fascinated with the place. "America became a romantic idea again to mef" he wrote recently in his online tour diary. "fan idea untarnished by the current administration's policies home and abroad. . . I will always be critical of Bush and his thuggish team but that shouldn't have any effect on my love of all the great things about the US: music, art, literature and movies that have shaped my life as much as any Americanborn kid. This idea of America wasn't the only factor in our sonic ambition being more thirsty but it played a much bigger part than ever before."

Now back home, and with time to reflect, Lightbody admits to finding the US "a scary place" that has lost a lot of its romanticism, perhaps in part due to the punishing tour schedule the band has undergone there.

"For me it happens in tiny increments. When you grow up you have this attitude that America is a 'you-got-it' attitude but the little things about American life get to youf the romanticism gets eaten away and you do feel far from home. That's not even considering the broader evil of the Bush administration.

But I don't want to get into the politics of things now. Christmas is coming and hopefully next year will be better [politically]" Lightbody will spend the holiday season with his mum, dad and sister in the family home in Bangor and then head off to the "wilds of Scotland in the middle of nowhere" for the new year.

Before that are this week's end-of-year gigs.

"It always feels like coming homing home when we play Dublin. We are a really lucky band in that we get to play three homecoming gigs: Belfast, Dublin and Glasgow. With two Scots and three Irishmen we are very proud of our heritage. When we are touring we are very much an Irish band. We are from the rock of Ireland and we have a lot of tartan and haggis infecting us. I guess we're Celts but it's hard to define.

"But we relish coming home and the Dublin shows are going to be really special. Martha Wainwright can't make it but Lisa Hannigan will be there and there will be one very strange and special guest . . . a bunch of people actually but I'm not going to tell you who. It's no one you know but hopefully they'll get a good receptionf" Snow Patrol play the Odyssey in Belfast on Thursday and the Point Theatre, Dublin next Friday and Saturday night 'Eyes Open' is out now