In the Nineties, the lead singer of Pulp helped the aged, sang with the common people and discovered hardcore - now, he is finally happy.

Amid the rumpled grandeur of West London's Cobden Club, the familiar angular figure of Jarvis Cocker stands out like a sore index finger. His sartorial signature of autumnal tweed might have acquired a more opulent, less scratchy look over the years, but Jarvis still exudes the same lanky raffish charm as he did a decade ago.

The woman doing his make-up for an interview video for the international press thinks a little dry shampoo might be a good idea, but Jarvis says not to worry: "All English men have greasy hair anyway."

When you consider the current status of his fellow former Britpop mainstays (Oasis's Gallagher brothers doing anniversary tours to pay the alimony; Blur's Damon Albarn pretending to be a cartoon) Jarvis is looking remarkably chipper. A lot of water has gone under the bridge since those halcyon mid-Nineties days, but whereas he once looked to be drowning in Britpop's backwash, the tide seems to have turned in Jarvis Cocker's favour again.

While photo-shoots and videos for Pulp's last album - 1998's coruscatingly doomy This is Hardcore - found Jarvis heavily made up, the 2001 model looks refreshingly unstyled and unapologetically himself.

With its optimistic title, We Love Life, and bucolic subject matter - songs called "Weeds", "Trees", "Birds In Your Garden", and "Sunrise" suggest Cocker has embarked on a passionate fling with Mother Nature - Pulp's new album certainly seems to represent a dramatic turnaround from This is Hardcore's gruelling litany of loneliness, impotence and paternal abandonment. And as to how this happy transformation came about, well, perhaps the emotional scars of seeing himself impersonated on Stars in Their Eyes just took a long time to heal.

"People always used to say 'You'll be in a really good position to deal with success, because you're in your thirties,'" Jarvis recalls wistfully, "but in a way I think that made it worse. Because at that stage you've already got a life, which is full of all these friends and relationships you've had for ages, and all that gets disrupted. It's like: 'You thought you had a life, mate, but all the stuff that's happened up to now, in your new environment that counts for fuck all'. I'm not saying that fame is automatically an awful, soul-corroding, spirit-dissolving thing... just that it can be."

Cocker has dealt with the downside of hedonism before, most notably in 1995's famously sardonic rave-culture commentary "Sorted for E's & Wizz", but he seems to have emerged from his own long night's journey into day with a bracing new perspective. "That's the trouble nowadays, isn't it? People think they've got a right to be happy and they haven't. Drugs can take you to places that you would normally have to do something to achieve, but I think on balance you're better off working to earn your happiness, rather than [Jarvis mimes ingestion of a tablet] 'Oh, I'm happy... [Jarvis mimes the passage of time] Oh I'm depressed...'"

All too aware of the creative pitfalls that accompany the reformed party animal, Cocker's new gospel of organic optimism is built on a trenchant foundation. "I knew I wanted to write about things that were more positive," he says, "without it being like 'Oh, this sad fucker's had to go for a rest cure in the countryside and now he's hugging trees rather than shagging make-up artists.'"

Jarvis's activities over the past few years have definitely had an air of mystery about them. Aside from the occasional guest vocal, the Channel 4 documentary Outsider Art, and odd sightings at Sussex village fetes with his former girlfriend, the American film actress Chloe Sevigny, you'd be hard pressed to know what he's been up to.

The first of the new songs were written for 1999's performance at the opening of a show by the painter Gary Hume, in the far-from-rustic surroundings of the Venice Biennale. The band performed in front of Venetian blinds - "When in Venice..." Jarvis says drily - and the quietness necessitated by the unusual location (the palace's priceless crystal chandeliers might have shattered if they'd played any louder) fed back into the music they were making in the Cocker residence in the Brit-art ghetto of Hoxton.

The new album didn't come easily though. An early version was abandoned and, had a performance at last year's Reading Festival not gone well, they might have knocked the whole thing on the head. But the rapt audience response to the current single "Sunrise" kept them at it.

The turning point was engaging the legendary pop maverick and longtime inspiration Scott Walker as producer. "He would say to our drummer 'Hey Nick, put some lead in your ass.'" Jarvis smiles with pleasure at the memory, "That was to make him slow down... And it worked," he marvels. "There really was a lot of lead in that ass."

We Love Life has turned out to be Pulp's finest and most complete recording to date: the band's music is more supple and more engaging than ever before, and Cocker's lyrics are as good as any he's written: at once effortlessly contemporary and occupying a world all of their own.

"Weeds", the anthemic opening number, begins with a rousing vision of the bravery of asylum-seekers and proceeds through a compelling meditation on drugs, prostitution and the exploitation of the underclass for entertainment, to culminate in a defiant statement of self-affirmation: "Do your dance, do your funny little dance."

One of the great pleasures of watching Jarvis perform with the pre-fame Pulp was the way he would ramble on between songs. But as the band became more successful people started hanging on his every word. Presumably that must have been rather disconcerting for someone who'd always insisted on his right to talk "complete rubbish"?

"I'm not a big fan of talking," claims Jarvis. "I think it's over-rated... What is it they say about empty barrels making most noise?"

Anyone who doubts the enduring logic beneath Cocker's deadpan anecdotal style should pay heed to his explanation why, at last year's South Bank tribute concert to the great folk archivist Harry Smith, he controversially recast the cotton-picking blues standard "The Boll Weevil Blues" as an imaginary conversation with a cockroach about to fall into a pan of spaghetti bolognese.

"Because I'm from the South Yorkshire triangle rather than the Mississippi Delta, I had to try and come up with some appropriate subject matter. As far as I could make out, the song is about a farmer telling this boll weevil not to destroy any of his crops. Now, when I was living in a squat in Camberwell, we had quite a problem with cockroaches, and I turned this Baby Belling cooker on one night and then got distracted. When I went back to the cooker, there was a cockroach doing a tightrope walk along the edge of the pan... I didn't have any money at the time and I knew if it fell in - desperate as I was - I wouldn't be able to eat the food because of the cockroach juice, so I was trying to persuade it to fall off the other way..." He looks up for confirmation of how exquisitely this inspired conceit harmonised with the concerns of the author of the original song. "And people in the papers slagged me off for missing the point!"

After so many years with his face pressed up against fame's restaurant window (Pulp recently entered their third decade, with Jarvis the only remaining founder member), it was no wonder his glasses got a bit steamed up once he got inside. Now he's seeing things more clearly again, does he think he's learned anything?

"It's certainly a privilege to have experienced what goes on in that world at first hand," he says thoughtfully, "rather than going through life labouring under a misapprehension of what it might be. The only downside is that when you see how something actually works, it often doesn't measure up to your expectations." Jarvis smiles. "But then I think even that's good because it gets rid of an illusion in your life, and you can get on with thinking about something useful."