With a hip new venue, a young enthusiastic host and a 20th birthday to celebrate, it was fitting that the winner of the Barclaycard Mercury prize went to a debut album feted for its innovative sound.

Indie act Alt-J won the 20,000 winners’ cheque — and the increased profile and record sales that are promised alongside it — for their album An Awesome Wave at the award ceremony at the Roundhouse in Camden, north London.

Joe Newman, Thom Green, Gus Unger-Hamilton and Gwil Sainsbury, who formed at Leeds University in 2007, have been one of the surprise successes of the year, coming from obscurity to become the favourite for the prize which was celebrating its 20th year.

Alt-J whose name comes from the shortcut for the delta sign on a Mac keyboard looked less like pop stars and more like recent graduates as they accepted their award with thanks to their parents and “team Alt-J”.

In perhaps one of the least rock’n’roll press conferences ever given by a Mercury winner — an event not famed for its guitar-smashing, hard-drinking superstars — shortly after winning the award the band were starstruck, but politely overjoyed.

“We are not really used to all this,” said guitarist Joe Newman, gesturing at the assembled music press. “We’re bowled over beyond belief.” Asked what the band liked about the album, keyboardist Gus Unger-Hamilton said the fact he enjoyed listening to it was testament to the fact it was “quite good”. He said: “I love it because we made it, it was just us at uni, just us four guys in a band.”

But despite promises to spend the 20,000 winning cheque on a slap-up meal for their parents — who would have to be shipped in from France, Harrogate, Cornwall and Southampton — it appeared that some of it would be spent on more immediate celebrations. “We are going to go and get really pissed,” said Newman. “Christ we’ve just won a Mercury award.”

The band beat musician turned actor Plan B and Pulp guitarist Richard Hawley, nominated for his album Standing at the Edge of the Sky. Giving a compelling performance in sunglasses and with a black leather jacket stretched over his midriff, Hawley missed out for a second time, having lost out in 2006 to the Arctic Monkeys, who said he was robbed.

In a bid to inject fresh life into the prize, organisers moved the event from the stuffy Grosvenor House hotel to the Roundhouse music venue in Camden, replacing longterm presenter Jools Holland with DJ Lauren Laverne.

The ceremony was broadcast live on Channel 4 after Mercury organisers and corporate sponsors Barclaycard broke off a long-term partnership with the BBC. The multiple gambles immediately appeared to have paid off as Plan B soul crooner turned hip hop social commentator tore up the stage with his riots-inspired track Ill Manors to open the show, throwing himself around the stage flanked by balaclava-wearing band mates.

The Maccabees gave a solid rock performance, along with other nominees Michael Kiwanuka, Jessie Ware, Lianne la Havas, Field Music, Sam Lee, Ben Howard and Django Django. Special applause was reserved for the jazz act Roller Trio, who floored the room with their squawky saxophones and urgent cacophony of sound.

The prize moved from September to November this year, making people think of the year’s music as a whole, according to Simon Frith, chair of the judging panel. He said it was fitting that a band’s debut album had won a prize that valued fresh sounds. “We hadn’t heard a sound like that before,” he said. “If it tells us something about music now it is that the concept of genres is problematic. All these albums are taking interesting things from all sorts of genres.”

Paul Stokes, associate editor of Q magazine, said the event appeared to have ushered in a new era for the Mercury prize. “There isn’t really one record that has summed up 2012, so whoever the panel picked, they knew there would be no consensus,” he said. “With that backdrop Alt-J is a good choice. It’s an innovative, arty, but engaging and warm record, which will surprise many and make sure the prize is talked about.”

Martin Talbot, chief executive of the Official Charts Company, said that in an unusually open field, Alt-J were worthy winners. “An Awesome Wave is almost an identikit Mercury winner, but also an excellent album,” he said.

The band had potential for mainstream crossover, said Paul Scaife, managing director of industry newsletter Record of the Day, despite the fact that the “man on the street” may not yet have heard of them. “I think the prize this year has been under increased pressure to be relevant,” he said. “Alt-J have some fantastic songs and are controversial enough to make the choice valid.”