By Greg Cochrane
Newsbeat music reporter
Anvil - The Story Of Anvil is released on 20 February in the UK
A group of gnarled old dudes with tired eyes, thinning hair and the wisened years to really know better are rocking the stage.
No, we're not talking about U2 opening the Brit Awards.
This is Anvil, the early 80s metal band whom after influencing some of the biggest names in their genre [Metallica, Slayer] somehow got forgotten and seemed destined to become a mere footnote in rock's bibliography.
The Brit Awards might be taking place six miles away down the road in west London but they might as well be in a different universe.
Here, at Anvil's celebration, the hair is much worse, the behaviour much wilder and the music much louder.
"The story needed to be told for many years," says drummer Rob Reiner ducking into a nearby karaoke booth to take a break from the party.
"Now I'm glad it's been told and people are engaging with it - everybody gets it and they want to see the band succeed.
"Soon the world will realise the majesty of Anvil - it is as simple as that."
Anvil - The Story Of Anvil is due out on 20 February and chronicles the ups and downs of a band who never relinquished hope and one Reiner himself describes as "a deep slice of life heart-touching buddy-friendship inspiration".
Anvil performing live in London
School friends Rob 'Robbo' Reiner and Steve 'Lips' Kudlow began the band 27 years ago.
Tonight though - a packed crowd of young and old fans moshing to Faith No More records before Toronto's heaviest play live - is Anvil reaping the rewards after three decades of largely unrecognised labour.
"Lips out of stage? He's a mind blowing entertainer and the music is indescribably amazing. That's an Anvil party," Reiner chuckles early on.
The film itself is perhaps not the hedonistic rollercoaster you'd expect from a fly-on-the-wall Rockumentary.
"The first time I watched it, it completely blew me away but it was too much to take in for me personally," says Reiner.
"Sasha [Gervasi - director] purposely made sure I was the last one to see it."
Like Mickey Rourke's The Wrestler meets Spinal Tap and soundtracked by thrash metal, the movie showcases the fight of the underdogs' battle to avoid obscurity.
It is a heart-wrenching insight - Reiner and Lips delivering children's lunches to get by in between playing increasingly smaller shows but never losing sight of their goal.
"I had knots in my throat at a few points," admits Reiner after watching the film. "We were just being ourselves anyway.
"We had a camera crew there - we let them film everything.
"But for me, to be brutally honest, the whole entire journey has always been a good time. Fun - it's the best religion."
As a makeshift merch stand sees Anvil T-shirts flying off the shelves, no-one here could care less about Duffy's dress and Coldplay's empty handedness over at the Brits.
"I hope they're having fun over there too," smiles Lips before asking who Girls Aloud are. "What's good for them is good for them. I don't take notice of those kind of things."
"As far as the award shows go they should have metal categories at all of them," says Reiner.
Come 1am proceedings end in a giddy hurricane of sweaty mullets and spilt cocktails as the band play live - and the future for Anvil looks far more promising.
Anthrax's Scott Ian and Anvil's Steve 'Lips' Kudlow
"Nothing has changed, we're just kicking ass all the time," outlines Reiner coming off stage. "Now there are more people to rock for and more people are understanding the story."
These veterans aren't even contemplating retirement. They're already confirmed to play this year's Download festival in June [headlining the third stage].
"Glastonbury could end up happening too. Even Reading," reveals Reiner. "We're planning on doing it all. Anvil has been around - now we're really going to be around."
Backstage Lips ends the night in slightly more reflective mood.
"I get to not do deliveries any more," he booms looking to the future. "To make a living from it - to actually make some money from it would be really a big change."
"Listen," he smiles. "I've been working on my diploma and I'm finally getting it - from the University of heavy metal."