Jarvis Cocker wants to reinvent the wheel. Again. Thirteen years since Common People, a stomping vignette about a rich girl sexually slumming it, brought Pulp's unique brand of kitchen-sink pop to the nation's attention, he's off again. This time, he's going on the road, determined to create a new type of spectacle. "I want it to be part show, part lecture, and part disco." He smiles at the ridiculousness of it all. Jarvis has got a lovely smile - knowing, a little bit ironic, but ultimately sincere.

His mini tour is partly to celebrate 30 years of Rough Trade records, home to the Smiths and, more recently, bands such as Arcade Fire and British Sea Power. Although Jarvis has only recorded one album on the label, his first as a solo artist, he has been managed by Rough Trade's Geoff Travis and Jeanette Lee for the past 15 years.

He's 45 now and wearing a reclusive-pop-star beard - black with a few sprigs of silver - but is otherwise little changed. He's still a stick insect of a man. A trendy stick insect, mind, with his carefully cultivated designer-Oxfam look: grey jacket, blue cords, a tie that thinks it's a cravat, spectacular specs and stack-heeled leather shoes taking him up to 6ft 4in.

We meet at Rough Trade, where we have been lent the marketing manager's office. I am sitting behind the desk, Jarvis in front, like a job applicant. I offer to swap places, but he seems to like the subservient role.

Back in the 1990s heyday of Britpop, there were three headline bands - Oasis with their no-nonsense classicism, Blur with their arty rock, and Pulp with their literary pop. Cocker sang and wrote the words, which resembled short stories written by a down-and-dirty Alan Bennett - the sour nostalgia of Do You Remember the First Time?; the bitter vengeance of I Spy, addressed to the husband he has just cuckolded and the world that has failed to embrace his genius; the pulsing desperation of The Fear when he realised success has made him even more insecure than he was in the first place. Often he was the hero, or anti-hero, of his own songs; sometimes he would appear in the third person; occasionally he adopted a female persona.

Cocker's epitaph could well be, "Be careful what you wish for, lest it come true." He grew up in Sheffield, a shy, gawky boy who was desperate to be a pop star. One of his heroes was Scott Walker, who became a huge success and then ran away from fame. Cocker continued to strive long after most would have given up, and eventually his band also became huge. He loved music and performing, but he hated success even more than failure and, like Walker, did a bolt. The "glory years", as he calls them with that smile, seemed to happen at hyper-speed. On one album, he was anticipating the big time and the perks it would bring; on the next he was despairing at the sell-out he had become.

I tell him that what I love about his songs is that he sounds as if he has spent a lifetime eavesdropping. "Yeah, well I have, I suppose," he says. His father left home when he was seven to make a life for himself as a DJ in Australia. From then on, Cocker remembers listening in on the chatter of his mum and Auntie Mandy, whose husband had also walked out. "I learned most things about the adult world from eavesdropping on my mother and her friends. There was another friend whose husband had also fucked off, so they discussed the various blokes they were dating. They'd talk in the kitchen over a cup of coffee and I knew if they shut the kitchen door they'd be discussing something quite juicy so I'd go and listen."

Despite the famous song, when he was growing up his family were considered anything but common. After all, he was called Jarvis, his sister was Saskia, his grandfather had a successful DIY shop, and they lived in a big stone home set back from the road, which had once been the manor house. It was only when he went to Central Saint Martins College of Art & Design as a mature student at 25 that he discovered what really posh people were like - people such as the Greek girl in Common People who wanted to sleep with him, largely because of his accent. He says he found it quite liberating to discover he was working class, after all.

Cocker is one of pop's great observers, and he has never observed anybody quite as closely or as critically as himself. I ask him what he thinks he's good at and what he's rubbish at. "Erm ... well ... I don't know. I guess I'm fairly insistent and maybe consistent. If I decide I'll do something, I generally will." He speaks slowly, pedantically, in an Eeyoreish monotone. Sometimes, he sounds so lugubrious you can forget how funny he is. "Pulp existed for 12 years before we got famous. Now, you could say that was just lack of imagination, but it's some kind of quality isn't it? Tenacity." He pauses. "You could also say it was sloth."

But he could also say he stuck with it because he loved it? "Yes, I think so, otherwise I wouldn't have kept doing it. The main thing I don't like about myself is an absurd level of self-consciousness that makes any sort of social encounter an ordeal for me."

He recently went on a trip to the Arctic with 40 artists and spent the weeks beforehand worrying how he would cope socially. In the end he enjoyed it, and he has determined to become more sociable. "I've been going out a lot more. You have to try yourself out on other people, don't you?" I ask him if his wife, the French stylist Camille Bidault-Waddington, thinks he's antisocial? "She thinks I'm a bit autistic, basically." They live in Paris with their five-year-old son, Albert. Has Cocker made friends in France? "Maybe three or four. You don't need more than that, do you?"

If he were so shy, why on earth did he want to be a pop star? "Oh well that's easy to answer because it's a way of being sociable but at a safe distance. You're on a stage but people are a bit away. You're singing songs that are a personal expression, but you're not doing it individually to people; you're doing it to a mass of people. I find it much harder to be open with someone I'm intimate with."

And that, he says, has always been the problem with him and his relationships. "Every woman I've had a relationship with has found this maddening; the fact that I will talk about anything on the stage, and reveal all this stuff, and yet when I'm at home, I clam up and won't discuss anything intimate or personal."

But he does express himself honestly in music? "Yes. But it must be unhealthy if you only express yourself in that area and you don't express yourself in your real life. That's a bit fucked up, isn't it?" He often turns his statements into a question. If he didn't express himself through music, wouldn't he go potty? "Yeah, I'd explode. As I say, that's what I think art's for."

In some ways success was great - the acceptance, the feeling that people were finally listening. But, he says, apologising for another paradox, he lost the most important thing to him - his invisibility.

"The way that I work is reacting to things that are going round and listening and picking up on what's going on, and to do that you have to be anonymous, basically. So my natural habitat disappeared. Then it becomes very internalised and that's not good for anyone."

There is a famous quote from his drinking, druggy days that sounds embarrassingly self-congratulatory. I recite it back to him. "I had access to the most quality fanny available." Ah, he says, that's taken out of context. "It is a bit embarrassing, I suppose, but it wasn't meant in a show-off way. It was more that they're the rock'n'roll cliches; they're the things that are supposed to bring you happiness, aren't they? You make it, and you're bathing in champagne and you can snort as much cocaine as you want and fuck as many beautiful women as you want. Then you find you can do those things, but they don't actually make you very happy."

How long did it take him to realise? "About six months."

Early on, he says, he really did believe Britpop was a new dawn - not just musically, but politically. If the alternative, rather than the mass-produced, could be embraced by the mainstream in pop, maybe that would be the harbinger of social change. "I had high hopes that it would be some kind of revolution within English society. But I think the mainstream is too strong. It's flowing too fast. These little jagged things go in there and they get smoothed off straight away."

What kind of revolution had he envisaged? "What makes society and life interesting is diversity, so if something that embraced that diversity could be accepted in the mainstream that would mean mainstream society would be more open and accepting. And that's what excited me about it. That that could happen."

He says he's always been a bit naive, and it was hardly the first time he had been pulled up short from his dreams. "I'm always going through these false dawns. It was the same the first time I went to a rave. I thought, this is fantastic, people are dancing all night, they're all being friendly to each other, they're not really drinking, it's not about pulling birds or having a fight. And I thought, that's got to have an impact on society. When they go home after being all loved up and talking to everybody and being really inclusive, how can that not have some knock-on effect in normal life? And yet it didn't." He smiles, baffled. "That was the last spontaneous youth thing. I can't think of anything that's not been stage managed since then."

Once the photographer's camera is on him, Cocker seems to relax. He explains why he wears heels. "It's like, what are you going to gain from wearing flat shoes? You're still tall, so why not just go for it? I admire that about Beth Ditto - she just goes, 'Here you are, that's it.' I think it's great. By not being ashamed of it, and accentuating it even, you turn it into something quite positive rather than something you're ashamed of."

The worst thing, he says, was seeing gangly, geeky Jarvis turned into a brand. "If you're an inadequate person, you make this thing called a group to give you something in life that you've got some control over, a little bit of a fantasy to escape things. And then that thing becomes popular. So that very personal almost self-medicating thing you've invented gets taken way from you and becomes a product. And in some way, your personality and your funny clothes and your funny glasses also become a product. So you start feeling you're part of some capitalist system. Something personal has been made into a commodity that is considered valuable. And I hated that." On This Is Hardcore, he compares himself to a pornography worker who has been violated through every orifice and then given the heave-ho. "But you have to realise you're complicit in that act. You're taking your clothes off in the first place."

In 1996, at the height of his fame, he protested at the Brit awards when Michael Jackson turned himself into a contemporary Jesus for a performance of Earth Song. Cocker invaded the stage and waggled his bottom disrespectfully in the direction of Jackson. There was a tremendous hoo-ha, which resulted in performing children receiving minor injuries as security tried to get Cocker off stage. It led to Cocker being labeled the antichrist by the press the next day, although he was later feted for ridiculing Jackson's messiah complex. This one act branded him more than anything as Cocker, the situationist prankster. He is all too aware that this is the first thing many people associate him with. Again, he knows he has no one to blame but himself. "I guess lots of people have one particular incident that overshadows just about everything else they've done in your life. Although I don't regret it as a moral action, the fact it will be the first line in my obituary is just a little bit disappointing. I'd like to think I'd given more to the world."

He says that after Pulp, he almost walked out on music for good. It was only when he was on the verge of quitting that he realised how much it all meant to him. Even though he's spent most of the intervening time in Paris being a dad and recovering his anonymity, he's involved himself in a surprising number of projects - writing songs for Marianne Faithfull, Charlotte Gainsbourg and Nancy Sinatra, curating the Meltdown festival, making music videos for bands, lecturing on lyrics, working on his second solo album and now the tour. And more than ever, he's determined to make it special - hence the mix of gig, lecture and disco. "Even when we were deeply unsuccessful we used to cover the stage with tin foil or hang things from the stage. People used to take the piss out of us, but I always thought it defined it as a night that's not the same as every other night in that venue - I think it shows a bit of respect for your audience."

Does he think this time around he can have success without becoming a commodity? "Well I hope so; otherwise I'm fucked."

He had been about to hit 40 when he considered walking away from music before. "I just thought, 'You're too old to be in a band.'" Does he think that he's too old now he's 45? "Yeah, but who cares? I am too old. I have resigned myself to the humiliation that goes with it now." I laugh. "I have!" he protests. "I have, because I realise it's the only thing I was born to do".