MEMOIR : Madeleine: Our Daughter’s Disappearance and the Continuing Search for Her By Kate McCann Bantam Press, 392pp. £14.99

EVERYONE SAYS THAT Kate McCann has got very thin. “She looks gaunt,” a woman said to me after her appearance last week on The Late Late Show, with her husband, Gerry. It is four years since their daughter, Madeleine, disappeared while they were on holiday in Portugal. The McCanns are now so saturated in public attention that their faces – well, Madeleine and Kate McCann’s faces; Gerry McCann is less distinctive – are etched on to our brains. And in that time our various obsessions about the adult McCanns have remained remarkably constant.

“Reports of my weight loss were greatly exaggerated,” Kate McCann writes of the period immediately after Madeleine’s disappearance. “In the first week I did lose about 4½ pounds, which I could ill afford, and which it took me months to regain, but nowhere near the stone removed from me by some of the press. I have always been thin. It’s the way I’m made.”

This is in several ways a terrible book. At its heart is a child who is missing and quite possibly dead. It is written by a desperate mother and was published on what is to be hoped was Madeleine’s eighth birthday, lest she be forgotten. It recalls the media circus sparked by the disappearance of Madeleine McCann in May 2007, from which no one emerged very well except, bizarrely, Clement Freud.

At the start the McCanns seem to have believed in the media. Even when they were too traumatised to be interviewed they were watching the big guns assembling: “Sky had three anchors in Praia da Luz. The BBC sent out Huw Edwards. ITV dispatched Sir Trevor McDonald, who did a one-hour special from the village.”

To read this book is a strange experience. On the one hand you feel that you have, literally, seen it all before. The writing is dull, and injections of information about, for example, how the McCanns’ sex life had to be revived after their daughter’s disappearance do nobody any favours. “I have wondered,” writes McCann, “whether we haven’t already given too much of ourselves and our family to the world.”

But the hell the book describes is so grim – the missing child, the peculiar police, the circling cameras, the crystals, the hoaxes, the cranks, the psychics, the private planes, the visit to the pope, the flowers and the teddies left by well-wishers – that you feel that you must respect it. “To suddenly become the focus of such attention – fiercely acute, and yet at the same time disconnected, impersonal, as if we were some rare species in a zoo,” writes McCann, “was bewildering.”

Every decade has its celebrated case, the terrifying case, that becomes a public spectacle. Madeleine McCann is ours. And eventually the accusatory stares turned on the McCanns themselves. (They later won £550,000 in damages from Express Newspapers.)

The McCanns were criticised for leaving the children unattended in the apartment, with the patio doors unlocked, although they explained that they checked the children every 30 minutes and were having dinner nearby. Kate McCann, besides being horribly guilty about this, observes the criticism coolly. “I have come to understand that some of these critics have been acting out of self-preservation. Holding us culpable in some way makes them feel their own children are safer.”

Kate Healy is an only child and an achiever. She works hard and is determined, “a finisher”, as she says herself. The first weekend after Madeleine’s disappearance she felt “a burning desire” to run up Rocha Negra, a nearby mountain. In the coming weeks she and Gerry did run up it. While running she would say a decade of the rosary. Her religious faith is one of the few unusual things about her, and their shared background, of working-class Irish Catholicism in Britain, was one of the things that united the McCanns – combined with the fact that Gerry, unsurprisingly, obviously fancied Kate Healy like crazy. The hymn On Eagle’s Wings was played at their wedding.

One gets the impression that Kate McCann was always a very good girl. Clement Freud, who had a house in Praia da Luz, gave her her first taste of brandy at this time. He had sent them a letter saying he was ashamed of the media’s intrusion into their lives and asking them for a meal. He cooked for them and, with his mordant wit, was one of the few people able to cheer them up in those terrible weeks.

You feel that McCann is a woman who has always followed the rules. In her relationship with the press her beauty was an asset, but her reserve was not appreciated. She was willing to show her wounds in the marketplace, if it got her daughter more publicity, but she refused to collapse in public.

The day before she vanished Madeleine said to her mother at breakfast: “Why didn’t you come when Sean and I cried last night'” Kate McCann is now convinced that an intruder had been in the apartment the night before. The three McCann children were left in the apartment with the patio doors unlocked for five nights in a row. This is a hard fact for the McCanns to live with, although the length of their ordeal now places them beyond criticism.

Kate McCann acknowledges that from the start, along with the inadequate Portuguese police investigation and the vicious rumours, people have rushed to help them. The businessman Philip Green lent them his plane so they could visit the pope. The British foreign office sent a former journalist, now an official media handler, to help them deal with the press. David Beckham appealed for Madeleine’s return. And now, on publication of this book, the British prime minister, David Cameron, has written that the McCanns’ ordeal is “every parent’s nightmare”, responding to Kate McCann’s open letter to him, printed in the Sun.

This is the unifying power of nightmare but also of sentimentality and of standing knee deep in cuddly toys. The missing child is the stuff of horror stories and of fairy tales. But most children who are abducted are hardly missed, and few people go looking for them. For now the tabloids are once more the McCanns’ friends. On the book’s publication Cameron instructed his home secretary, amid some controversy, to let officers from the Metropolitan Police review the case. No one would begrudge the McCanns this, but in Britain it has been pointed out that not all parents of missing children get that support.

As for Madeleine , it manages to be at once very sad and pretty monotonous. McCann is not the person to do justice in book form to the tragedy and the mystery here, even though they are her own. It is difficult to see why anyone would buy it for anything but charitable reasons: all royalties go to Madeleine’s Fund, to continue the search for her.

Ann Marie Hourihane is an Irish Times columnist