New rock documentary Supersonic is a fascinating in-depth look at the incredible ascension of Britpop icons Oasis, following them from their formation in 1991 through to their legendary zeitgeist-tapping gigs at Knebworth in 1996, when a staggering 5% of all Britons applied for tickets to the two shows.

Directed by Mat Whitecross, the film offers a riveting look inside the inner sanctum of Oasis and how the differing world views and approaches amid this sudden mind-blowing success - particularly between the Gallagher brothers, Noel and Liam - manifested in acrimony (and occasional violence), eventually tearing the band asunder.

Oasis' record label boss Alan McGee - who ran indie behemoth Creation Records, also home at the time to acts like Primal Scream and My Bloody Valentine - plays a major role in both the band narrative and the documentary, and he believes that for the most part Supersonic is an accurate representation of what transpired during these crazy times.

"Liam might I think reform Oasis in a few years' time without Noel."

"As much as you can view anything 20 years later it felt like it rang quite true," he reflects. "The times were crazier than that, but at the end of the day what can you really say to show that properly? It just was what it was. It was crazy times the '90s, and they were crazier than what they could show in the film but I think they captured the spirit. It's a very good film."

McGee famously discovered a then fledgling Oasis at a Glasgow gig where they were opening for one of his bands 18 Wheeler, signing them on the spot.

"It was a complete fluke to be honest," he smiles. "Glasgow had just been named 'European City of Culture', and to even mention Glasgow in the same sentence as culture is a joke - Glasgow is one of the most un-cultural cities in the fucking world! Being in Glasgow was like being in Poland, only with more rain. But I just happened to be there, and because it was a 'city of culture' the pubs were open 24 hours a day and the bands would go on late - instead of going on at half-past-eight the bands would go on at ten - and so I saw the first band and at that was Oasis: it was just luck that I saw them.

"Of course nobody saw what happened next coming - nobody knew they were going to be that big. In a way, it went too big. Creation was well-positioned, being a big indie, but it went way beyond that really fast. When it got to Sheffield Arena in early '95 it was already getting really fucking big then and that wasn't even half of it yet."

Supersonic paints a picture of McGee if not cultivating then at least revelling in the 'bad boy' image that quickly attached to the band.

"I didn't really have any option other than to embrace it - what was I going to do?" he laughs. "They didn't need any encouragement. But to be fair I was worse behaved at that point than what they were anyway, right up until the point when I got sober."

McGee tells that while he often witnessed the fractious nature of the Gallaghers' relationship firsthand, it was fortunately usually at arm's length.

"It was probably more difficult for the manager, I was just the record label and had signed them for the records," he laughs. "It was probably tougher for Marcus [Russell] - he was fucking incredible. Maybe Marcus is the unsung hero of the film to be honest. But with Noel and Liam's relationship I think it started as comedy, and then it became reality when they became big. But I honestly thought the antagonism started as comedy, playing up the media and everything."

Yet Supersonic also highlights via in-depth interviews with the brothers (naturally recorded separately) as well as their family members and bandmates - transposed over largely unseen archival footage from the time - how this intense relationship and sibling rivalry was also an integral part of the band's musical and interpersonal chemistry. Sadly it's also the reason that McGee believes there will never be a full-blown Oasis reunion.

"They'll never get back together because of Noel - Noel will never go back to Oasis," he states emphatically. "Liam might I think reform Oasis in a few years' time without Noel, just because he'd be keen to play to ten thousand people a night singing Oasis songs - I could see that happening - but I can't see Noel re-joining Liam and it being Oasis. I just can't see it happening."