David Baddiel is in the middle of writing an article about the crisis in masculinity when he meets me for lunch near his home in north London to talk about his second novel, Whatever Love Means (Little, Brown, £14.99). He's finding the concept problematic, largely because he doesn't believe it exists, but he seems surprised and mildly bothered to find himself labelled 'a standard-bearer for New Laddism', which is, he says, 'an appalling idea'.

This response seems somewhat disingenuous, given that Laddism was a niche he carved early in his career as a reaction against what he describes as 'a rather strangulated form of political correctness'. Much of his comedy material, particularly his stand-up shows, and, to an extent, his best-selling first novel, Time For Bed, were part of this manifesto; ruthlessly frank confessions about sex, masturbation, pornography, the grubby inner reaches of the male psyche - often very funny, but often deliberately shocking. The lyrical description of anal sex in Time For Bed became notorious.

Whatever Love Means comes as something of a surprise, then. It's a darker, more serious and thoughtfully-plotted story whose greater themes are death and grief; sex is still central but is touched with fatality. But Baddiel corrects me sternly when I suggest that this book marks a new direction in his writing, the emergence of a serious side that has come with age (he's now 35).

'Although Time For Bed was a comic novel, it had a lot of melancholy and serious undertones,' he explains. 'This book is the obverse in that it is tragic, but does have a lot of funny bits, so there is a sort of progression between the two. But a lot of the comedy I've done about sex and pornography has been quite dark, and with Newman and Baddiel In Pieces we did a lot of jokes about death. I still believe that comedy is the only way to combat death. I don't think I've suppressed my serious side in the past just because I enjoy making jokes about football.'

He objects to the note of condescension he detects in even the positive reviews - 'this sense that "Hasn't he done well - for a comedian" ' - but acknowledges that with the new book he is aiming for a difficult balance. 'Someone in the audience came up to me after an event I did at the Cheltenham Literary Festival and said, "That's the least funny you've ever been." Some fans will be disappointed that the new book isn't funnier.'

Whatever Love Means is the story of an illicit affair that develops between Vic Mullan and Emma, his best friend's wife, triggered by the emotional frenzy that followed the death of Diana. The affair continues for a year until it is brutally cut short by a tragic accident closer to home, overshadowed by the twin spectres of cancer and Aids. Baddiel wrote the book in just under a year, but the idea had been with him for a while, growing from a time when a number of his contemporaries died unexpectedly.

'It was a strange period in my life, and it meant I started thinking about mortality much earlier than many people have to,' he says. 'It made me realise that death really is terribly random, which is not great insight, but you don't know that viscerally until you experience it, and it seemed to me there was a lot you could learn from that experience. I was interested in writing about sex and death, and what it would be like to be having an affair with someone who died.

'Then when Diana died, I thought it would be a good background, because it was immediately assumed that her life did have a tragic trajectory. The hysteria that followed felt similar in intensity and madness to the beginnings of a sexual relationship, and I do know a couple of people who told me they began relationships on that day.'

Vic, the character in the book who appears closest to Baddiel's public persona, describes the public grief as 'emotional fascism'. Joe, Vic's best friend and the cuckolded husband of the novel, understands it less cynically as 'significance demanded' - the knowledge that one is part of a historical event that could be perpetuated by demonstrably grieving.

'It's very rare that you can feel you're part of a national and historical moment, and we all could with the death of Diana,' Baddiel explains, though he is concerned that Diana should remain merely a backdrop. 'She's a symbol throughout the book - when she died she became a symbol of sex and death, replacing Marilyn Monroe, but over that first year there was an incredible falling-off of public interest, having been the most intense cultural phenomenon.'

Despite being very firmly of its time, the novel barely mentions contemporary politics. 'I have a very apolitical nature these days,' says Baddiel, although as a student at King's College, Cambridge in the mid-Eighties, he was arrested on a Stop the City march, wrote for a left-wing journal called The Ranter and then went on to write material for Week Ending, which he blames for breeding 'a whole generation of writers for whom the central direction of comedy was writing skits on the week in government'.

The rise of Laddism was a reaction against this stream of right-on thinking, although Laddism as represented in the late Nineties by Loaded and its ilk is now exhausted, according to Baddiel. He sums up the Loaded generation in the novel as 'men who in their twenties would've been politically correct to be rebellious, and who now had to be politically incorrect to be rebellious, instead of realising that the dignified thing to do is to stop being rebellious'.

This seems a very grown-up statement from a man who asserted two years ago in an interview that 'I'm deeply immature and don't want to grow up', though not as surprising as learning that he identifies more closely with the character of Joe, whom he describes as a 'thinking, concerned, conscientious father'.

Baddiel does not have children but says he would like to; in Baddiel's Syndrome, the sit-com he is currently writing for Sky TV, his own fictionalised character has a young son. He wants to write more novels. 'If I had to concentrate on one thing and give up everything else, I would choose writing novels. Having said that, I would find it hard to give up performing completely because the narcissistic part of me loves doing it.'

Suddenly he glances at his watch and asks, apologetically, 'Can you lend me a quid for the parking meter?' It's only as he bounds out of the restaurant with my last £2 that I remember the £5.5 million he got from Sky for Baddiel's Syndrome - chivalry hasn't overtaken him just yet.