It looks as if the evening will end with Jamie T slumped in a backstage corridor with blood spattered across his white vest. In the dressing room, his band, the Pacemakers, are exultant, cracking open cans of Kronenbourg, their debilitating hangovers of earlier in the day now vanished in the wake of a blinding gig at Northumbria University in Newcastle. But it's the rigours of the show that have left their leader shattered: two songs in, the lights went up on the crowd and he'd thrown himself onto a sea of hands; carried to the back, he clambered up into the high-raked seating area and urged the fans there to pile down to the front. "I'll start picking on one of you in a minute!" he warned. With his mike chord stretching back to the stage, he started a version of his Top 10 hit "Calm Down Dearest", with the crowd of students and Geordies singing every syllable back to him, followed by a chant: "Jamie! Jamie!"
No wonder he's spent after the gig, but then when I met him at teatime earlier in the day, he was already in the pub, drinking a pint with a sambuca to chase it and asking if we could sit outside so he could smoke. He had with him a bag of records that he'd just bought second-hand: a Fats Domino LP, the soundtrack to The Rocky Horror Show, an Iron Maiden album and more, all on vinyl. "I shouldn't really have gone into the shop," he admitted, pale of face but grinning, eyes flitting from side to side. Like much of what he has to say - in interview and on record - his reasoning could have been clearer, but the gist was there: "I wiped about six grand's worth of music off my iTunes by mistake; the computer got blocked up so I tried to - this is fucking stupid - I tried to put my music on a hard drive, but I was watching that Martin Scorsese blues thing at the same time, and there's this great bit about space in it and how someone put this Blind Willie McTell record out into the stratosphere...
"So I deleted it off my computer," he continued, as his carrier bag blew away across the street, "but I also deleted it off my fucking hard drive... so because I don't have a CD player, the only thing I own now is vinyl."
It's not easy to pin down the 23-year-old Jamie Treays. Despite critics raving about his Mercury Prize-nominated debut Panic Prevention - the Observer Music Monthly made it their second-best album of 2007 - no one was sure whether to call him a singer or a rapper, or whether the record sat within the traditions of punk or hip-hop. Starting with the bewildering rallying cry "Fucking croissant!" the tracks careered past with an energy reminiscent of the Clash, the lyrics dense with imagery spat out to conjure an impressionistic picture of young London: "Girls singing on the bus, fellas kicking up a fuss"; the reek of a crack pipe in Trafalgar Square; the splash of spilt lager and subsequent recriminations. There was even a sample of John Betjeman, reading his poem "The Cockney Amorist".
In person, he's mischievous, often evasive, with words whistling through his crooked gnashers. I say to him that no one knows quite what to make of him and he says, smiling: "I know, but I like that. I do whatever I want, I'm not watching anyone else, I'm not trying to fit into any box."
Revelations that he comes from a middle-class family in suburban Wimbledon, and for a period went to the same Surrey public school as Tim Henman, might have invited scrutiny of his authenticity, but this rather misses the point that ever since the Rolling Stones emerged out of Richmond, the social mobility that has energised British pop has worked both ways. His birthright lets him mimic Bob Dylan to me one minute, the comedian Chris Morris in character as ragga singer Carlton "Killawatt" Valley the next and then sing a snatch of Queen ("I texted my mate once to say I thought they were the best pop band in the world, and he texted back: 'That's a funny way of coming out...'")
Endearingly fogeyish, he says the last gig he went to was the Specials at Brixton, and "I've heard of this Twitter thing but I don't really understand it. I don't want to sound like a dick, but I don't use the internet much". But he's keen to leap to the defence of his own generation, too, even if he'll run a mile from being painted as their spokesman. "I don't know about modern music much," he'll say, "but kids today are probably more like kids in Japan. From what I know, which is very little, I've never been there, they go out in punk rock gear and the next day they're Teddy boys. Culture is changing - it's put on, put off. But I don't think there's anything wrong with that. It's a new generation and all you old cunts can fuck off! It doesn't mean there aren't still [different pop] tribes, and people grow up in the same old shit."
Lurking on the edges of his song is a political awareness if not an agenda. "I don't talk about politics because it's not something I'm educated in," he insists. "It annoys me when people start getting righteous in bands. But then again some of my favourite bands are pretty righteous. Ha ha ha!"
It took 18 months to tour Panic Prevention, of which Treays says with a puff of his cheeks: "I'm not saying it's a hard job, because it's not, but it does take a lot out of you and at the end there's a bit of Vietnam veteran syndrome. I was having a hard time." Hunkered down in the studio constructed in the shed at the bottom of the garden of the house that he now shares with his older brother - down the road from their parents - he started work on an album of acoustic songs. "I've got a friend who likes wearing brown cardigans and Ray-Bans and sitting around feeling depressed about his life and he introduced me to people like Ryan Adams and a lot of folk. And I hate the way people say 'I found Dylan' but ... that's what happened!"
Despite this, Treays soon found he was bored of this new direction and he scrapped the sessions. Instead, with his friend Ben Bones, who produced Panic Prevention and plays drums with the Pacemakers, he started piecing together the scarcely less polished but even better album that will come out in August with the title Kings & Queens. It's preceded by an EP this month which gives a good taste of the new material, particularly the title track, "Sticks 'n' Stones". Laugh-out-loud lines include: "As I travel down the track all my memories flood back/ We were running like infantry men back to your mamma's flat/ It's the only place but home I feel relaxed enough to crap/ I know it sounds crude, but there's something in that."
"It's based on real life," Treays says to me of the song over his second lager. "It's the idea of: 'I remember you smoking weed in the park and now you're working in the city. What's going on?' I don't really know any stockbrokers, but then again, when you're writing songs, you can make things up. What annoys me is, though, is when people ask me what my songs are about. It fucks me off. Find out for yourself! I fucking wrote them - listen to them. I don't want to sit here and talk about them."
Pity his poor A&R man. "We rang him, man, and said: 'We think we've got the single. Yeah, we think it's really good, it's wicked.' We'd found all these lift versions of songs" - classics rerecorded as muzak - "and we sent him 'Highway from Hell' with me singing it like wosshisface from AC/DC and it was really horrible. I know he wasn't amused. I found it fucking funny. Oh well."
Following that evening's gig and sweat-stained singalongs of hits past and future, it doesn't look as if Treays is in any state to speak, but it turns out the blood on his T-shirt is simply the result of a nicked thumb, and he's soon enough on his feet again and heading off to a student ska night. "Pressure-wise, if anything gets too much, I just run away," he had said earlier. "I still get freaked out when people know who I am, it's still uncomfortable- although I love performing. I can't work it out myself!" He concludes: "As the Eagles said, just take it easy."
• Caspar Llewellyn Smith is editor of Observer Music Monthly. Jamie T's Sticks 'n' Stones EP is released on Virgin tomorrow
