We all have them, friends or lovers who will remain forever 17 or 24, frozen in time by memories or photographs at the moment we saw them last.

Like a negative of Oscar Wilde’s Picture Of Dorian Gray, they hold their youth and beauty in our mind’s eye while, out of our sight, they galumph their way into podgy middle age in the real world, losing their hair and their ideals along the way.

Linda Grant plunges straight into this world of nostalgia and unfulfilled promise in her latest novel, We Had It So Good, an affectionate but devastating dissection of one of the greatest living clich�s of our time – the north London family falling ever so quietly apart.

Stephen Newman and his wife Andrea, the couple at its heart, are the babyboomers who failed to launch. Stephen, an academic self-starting Californian, who sailed across the Atlantic to Oxford with a charming Southern fellow Rhodes Scholar called Bill Clinton, meets and falls for intriguing, velveteened hippy Andrea during a dope-fuelled summer picnic in the 60s and they tumble into a life together.

Unhindered by the chaos, poverty and loss which propelled their parents through war, emigration and yet more war, they drifted into the comfy but unsatisfying porridge of middle-age like wasps into a jam-smeared Boden trap.

Their parents suffered and struggled so they would be free to change the world. His making a new life in America from Cuba and Poland, hers battling the shame of genteel failure to crush their children in a loveless failed business.

Their parents’ generation may have been stuck on tramlines but at least they got somewhere. Poor old Stephen and Andrea seem to be so dazzled and paralysed by the fairground of choice which they are brought up into that they get stuck on the carousel.

The plot of We Had It So Good had, explains Grant, been brewing for some time, ever since 9/11. Then, for the first time in her life, she shared a shiver of the dread her parents must have suffered as they fire-watched over a war-torn Liverpool during the Second World War.

“When I was sitting here the following day, I really became convinced that Britain would be the next target and it seemed very obvious we were coming to the end of a period which, for this generation, we had just sailed through,” says Grant. “We had no wars, we had not been seriously affected by history and it started me thinking about my own generation.

“The second thing that happened was at a party, about five years ago, and I bumped into this well-dressed man with his great hair and his suit.”

It turned out that they had known each other at York University when he had been an idealistic hippy who set up a brown rice and joss stick emporium which had been the talk of York. Grant remembered the place, and the man, perfectly, or as it turned out, imperfectly.

“I asked him what he was doing now and he said, ‘Advertising’, and I began to wonder how do we get from there to there. How does that happen?”

The answer of course, is time and circumstance. “When I first knew him, he was barely out of his childhood,” she says but, in her mind’s eye, he was forever the go-getting life-changing hippy with an eye for a market in mung beans. But, as she pointed out, 30 years, a couple of children and a house to provide for changes your focus.

Grant was brought up short again by a similar experience once the book was safely written, when curiosity drove her to search out an old student friend online. The young barely out of his teens friend of her memory had long gone, she says, replaced by someone posting photographs of his grandchildren on Facebook.

By then, she had become fascinated in the clash of the generations and the process by which yesterday’s idealists become today’s slightly ridiculous, slightly tragic social stereotypes.

“I was going to have them live in Vauxhall or somewhere quite unfashionable,” she explains. But having decided to focus on one clich� of the age – the plight of the babyboomers – she felt she ought to set them in their natural habitat.”

“I wanted to get to the heart of the clich�!” she said. “I remember Islington in the 70s, how poor it was and how totally unlike it is today and chart how it became what it is today.”

And this she has done – with often quite heartbreaking accuracy and insight.

She describes Stephen as “ridiculous” in that he is slightly washed-up, slightly infantile and, of course, ultimately failed to reach his potential, whatever that was. But the tragedy is that he is only ridiculous to those who matter most to him, specifically his chlldren, who have been brought up on the tales of his finest hours and so can never ever find them even diverting, let alone, inspiring.

Is she a babyboomer herself? Chronologically and temperamentally yes, she says, adding that, at 59, she is plum in the middle of the postwar baby bulge and, temperamentally, she was raised to have ideals and dreams, not work for the man.

“I don’t know one person of my generation who wanted to work for a bank or be a corporate lawyer,” she says. But it’s hard to find anyone among her friends’ children who want to do anything else.

Undeterred, she continues to carry the ideological torch which was sparked in her youth. She recently joined the Labour Party because she couldn’t bear not to take part in the leadership battle (she is a surprisingly ruthless fan of Ed) and is currently incensed by the cuts to libraries and bookshops near her home near Alexandra Palace.

As babyboomers go, she has made her mark. She’s won the Orange Prize, been shortlisted for the Man Booker and, with this latest novel, has really hit home. Depending on your circumstances, it can serve as a prescient analysis of your parents’ lives, a timely wake-up call or, if you’re not careful, will stop you in your tracks and bang you to rights before you can say “Cancel the veggie box, I’ve been out-sourced.” Proceed with caution.

o We Had It So Good by Linda Grant is published by Virago priced �14.99. Linda Grant will be discussing her book at Keats House, in Keats Grove, Hampstead, on Thursday February 24 at 7pm. Doors open at 6.30pm. Tickets (�5 including wine) are available from Daunt bookshop in South End Green in person or on 020-7794 8206.