The day after Noel left the band, he posted a statement on Oasis's website. The parts bemoaning the "verbal and violent intimidation" from Liam were no shock: the two had been at loggerheads for years. More surprising was Noel's complaint about "the lack of support and understanding" from his bandmates.

Liam almost explodes at the mention of that line. "Absolute fucking bollocks. That's the thing that makes me want to throw up. I just look at him now and think, 'You're a fucking fake.' It's like, if you want to fucking leave the band, leave the band. If you want to stay at home with your kids, stay at home with your kids. If you wanna have five years off, have five years off. We'll sit down as a band and talk about it. But don't start going, 'I was bullied out of the band.' Fucking shite."

Archer sighs. "That statement was surreal as fuck."

To the outsider, I say, it read like Liam and Noel had a huge row, and Noel was hurt that the others didn't back him up.

"Noel doesn't need backing," says Archer.

"Back him in what?" snorts Gallagher.

What, then, do they think he meant?

"I think he wrote it on the spur of the moment," says Bell, ever the peacemaker. "He's probably mortified now."

"Not that mortified, cos he's still got it up on the fucking website, which I've tried to take down," spits Gallagher.

"Has he?" asks Archer.

"It's been two fucking years," says Gallagher, sounding increasingly angry and hurt. "Take the fucking statement down. It's over. We're all grown up. We've all moved on."

They've moved on in many ways. There are broken televisions lying on the pavement outside the expensive London hotel where we meet; inside the hotel's boardroom the talk is of uppers and downers. Fifteen years ago, you'd have put money on the TV sets having been thrown from one of the hotel's upper windows, and the uppers and downers being amphetamines and barbiturates. In fact, the televisions have been left for collection by an engineer, and Beady Eye's members are discussing not drugs but coffee and hot chocolate.

It took alcohol, though, to give them the bravado to make the decision, immediately after Noel's departure, that they would continue as a band.

They could, you'd imagine, have played it safe and soldiered on as Oasis. After all, Liam chose the band's name back in 1991, before his brother even joined. And Noel's exit announcement did say he'd "quit" Oasis, rather than disbanding them. But today, gathered around the boardroom table of the Landmark hotel, sipping their hot chocolates, the members of Beady Eye insist continuing Oasis wasn't an option.

"Going around playing someone else's songs?" says Gallagher. "That's not cool, is it?"

"Oasis is an entity that is to do with Liam and Noel," agrees Bell, the mild-mannered former Ride guitarist who, like Archer, joined Oasis in 1999. "It was much better to go, 'Right – new band, new songs.'"

After a summer spent recording with producer Steve Lillywhite, the result is Beady Eye's debut album, Different Gear, Still Speeding. It is, predictably enough, a rock'n'roll album in thrall to the Stones, the La's – an old band of Sharrock's – and, of course, the Beatles. What's more surprising, given that Noel Gallagher was widely regarded as Oasis's only songwriting talent (and then as a diminishing one), is that it's quite good.

That's not to say it's a masterpiece. There are moments of toe-curling banality, but there are some fresh and impressive songs, too. If you didn't like Oasis, Different Gear, Still Speeding won't convert you. But if you found anything to enjoy in their last few records, it will be a treat.

If it had been an Oasis record, that band's fiercely loyal fanbase would presumably have already done the preordering necessary to have made it their eighth consecutive No 1 album. But success for Beady Eye isn't so assured. The band's first proper single, The Roller, stumbled into the charts at No 31 last month – not the ideal result for a singer who enjoyed 22 consecutive top 10 hits with Oasis.

"You'd prefer it to go in at No 1, wouldn't you?" shrugs Gallagher. "But it didn't happen."

His bandmates gamely begin to explain that the posters for the single haven't gone up yet and that the 7-inch is still to be released, but Gallagher interrupts them.

"Look, as far as we're concerned, that fucking tune is shit hot," he bristles. "Production-wise, singing, playing, the words – the lot. We couldn't have done any fucking better. That's the kind of music we like. If that's not what's fucking hip at the moment, then listen, we don't change our style. We'd like to be No 1 and everyone to be on the same page, but it's not gonna happen, is it? You ask George Bush that, do you know what I mean?"

Um, not exactly, no. But it is abundantly clear throughout our interview that although Gallagher is calmer and friendlier than he was when I first met him more than a decade ago, he's hardly averse to proclaiming his own greatness.

"Look, there's a big fucking spirit up there," says Gallagher, glancing skywards. "It was in Oasis and now it's in Beady Eye. And it said, 'If you think you're having a year off, you little fucking prick, you're tripping. Get out there!' And thank fuck for it. We used to speak about Oasis wanting to be the best band in the world. Well, that's how we feel in this. We wanna go round the world. We wanna inspire kids. We wanna play some great fucking gigs."

Beady Eye will play their first ever show at Glasgow's Barrowland on 3 March. When they do, they'll blast through their album, a B-side and a cover of a track by the early-90s Manchester band World of Twist. But they won't play any Oasis material. "That's where it's really gonna happen," says Gallagher with certainty, record sales be damned.

I happened to be in the audience the last time the four bandmates (and Noel) shared a stage. That was seven days before the Paris showdown, when Oasis headlined the Staffordshire leg of the 2009 V festival. Before them, a vast crowd bellowed, embraced and air-punched their way through the set. It's hard to imagine the Glasgow crowd will match that.

"It's a big ask," agrees Archer. "It could be Elvis fronting the Beatles up there, but if it's all brand-new songs … " He trails off. "It's gonna be a challenge."

"They're gonna fucking love it, mate," insists Gallagher. "I know what they like. We've got the same DNA. They're gonna dig it, cos we're gonna be on form, man. That's why we're rehearsing like fuck."

And if people do shout for Oasis songs?

"I've got a microphone, we've got guitars, we'll drown them out," says Gallagher. "They can shout what they fucking want."

It does, I say, seem a bit sad that he'll never sing those songs again.

"I did the whole Knebworth set in the shower earlier," Gallagher fires back. "It was fucking great."

Not for the first time today, all four members of Beady Eye fall about laughing. Without his older brother around to push his buttons, Gallagher seems steadied and contented, talking proudly about his kids, his fashion label and, of course, the new band. "We're having the time of our lives, mate," he says, to general agreement. It seems unlikely they'd have said the same in the final days of Oasis.

"I kind of felt it was winding up, man," says Gallagher of those last months. "There was loads of little things going on. Noel was removing himself from the band, travelling separately, even though they [the media] were saying I was. And you couldn't speak to the fucker. Minute you brought something up, it was just a stony-faced: 'What are you gonna do about it?' But it's my band as much as his. I had to have my say. And he didn't like people standing up to him. So he grabs the ball and does a fucking runner."

Never one to concede weakness, Liam insists the Oasis breakup didn't hit him hard. "No, because, like I said, I'd seen it coming. I weren't ever really that close with Noel anyway. I'd only see him on stage. Gem would see him more than me."

Archer, Bell and Sharrock were all personally recruited to Oasis by Noel. But Archer was his closest friend and ally. "Noel was a massive part of my life," he says.

For now, though, Noel has disappeared, and neither camp shows much interest in making overtures to the other. "I'm in no rush to get on me hands and knees, and I'm sure he's fucking not," says Gallagher.

After everything they've been through, it would, I suggest, be a pity if they went to their graves without putting it right.

"That's well heavy," says Gallagher, his tone immediately softening. "Look, if I found out something was going on, I'd definitely send him a postcard, do you know what I mean?"

They will, he insists, eventually settle their differences. "Without a doubt. But I suppose I've got to grow up a little bit, and I suppose he has. People think I'm just a fucking lunatic, but Noel can be a little bitch, too. Maybe the pair of us have to sort ourselves out before we do that. But not just yet." His scowl gives way to a smile. "But thanks for your concern. I didn't know it meant that much to people."

The legions of Oasis fans for whom it means the most shouldn't get too excited by Gallagher's notional olive branch. He is convinced Beady Eye are here to stay, talking excitedly about the soundtrack they are set to record for the film about Apple Records his production company are making. "That can open a mad door for the next couple of Beady Eye records."

Inspired by the music Neil Young and Paul Weller have made well beyond their 40th birthdays, the 38-year-old is fired up about his future as a musician. But an Oasis reunion, Gallagher insists, simply isn't going to happen.

"Never," he says firmly. "This is not a stopgap until me and Noel come to our senses and start Oasis again. That is well and truly done."

"And now we're working on tomorrow's nostalgia," says Archer, brightly.

The band's press officer arrives to call time on the interview. Rising to head for a cigarette, Gallagher delivers his blunt, bullish and not inaccurate summing up. "We split up, we started a new band. Some people will hate the album, some people will like it. Some people will slag the gigs off, some people will love them. End of fucking story."

Different Gear, Still Speeding is released on Beady Eye Records on 28 February.