The Lost Child, By Julie Myerson

Early on in Julie Myerson's new book, she describes what the textbooks call an "intervention". "You get a whole crowd of people, relatives or friends who really care about your child, people who have been part of his life, to tell him he needs to go to rehab. But it has to be a surprise ..." As interventions go, The Lost Child has been pretty startling. A whole crowd of people – relatives, friends, Newsnight, the Daily Mail – has cornered Myerson's family to tell them what they think. Bloomsbury has rushed the book to publication. Hardly anyone in the country seems not to have an opinion about whether or not Myerson's child needs to go to rehab. It's been a surprise, all right.

The book started out, the story goes, as a social history along the lines of Myerson's big success, 2004's Home: The story of everyone who lived in our house – but this time about a young woman, Mary Yelloly, who died in 1838 when she was only 21 years old. It was a story of girlish detective work and cheerful, long-lost Yelloly descendants saying, "But of course you must join us for lunch while we fetch that dusty old box we have in the attic ..." But as she pieced together the details of this consumptive, long-ago family, her own was falling apart. She and her husband had evicted their 17-year-old son from their home, believing him to be in the grip of a destructive addiction to skunk. It was clearly hard to concentrate on a dead Georgian girl.

The blurb at the back of the book draws the following parallels between the two stories: "What happens when a child disappears from a family? What will survive of any of us in memory or in history?" But the book that came out of this tumultuous period is less a symbiotic interweaving of these two narratives of lost children, separated by centuries; more a fatal car crash of one overpowering story into another. It raises interesting questions about a writer's life. How much should and do her own experiences find their way into the writing? Can one ever write well about pain from a position of true pain? Is life, as Nora Ephron said, copy? And if so, how much of someone else's life is a writer entitled to?

The first thing that is striking about The Lost Child is pain –the pain of a modern family as it fractures and the pain of an 19th-century mother as she loses child after child to consumption, fever and "shock". Its first chapter introduces Mary and her sister: "Two young women, one dead, one alive. The living one holding the dead one tight in her arms. The dead one's loose hair already wet with the living one's tears." It is the first of many images of death. It will undoubtedly provoke Myerson's critics to tell her to pull herself together: her child is not lost. But evidently it feels as though he is.

"I don't want anyone to ask my how I am because I don't know how I am," she writes. "OK, I do. I am raw. I am boring. I am flattened, deadened. I have nothing in my mind except the deep black hole that is the loss of my child." If happiness writes white, the problem with misery is that it usually cannot write at all. But here it is given eloquent expression. Never has a book contained so many startling metaphors for loss.

Myerson describes the book, to her son and subsequently to her critics, as "a book about how much I love you ... though I realise you may not choose to see it quite like that." This must be the tough love that the drug counsellors talk about, because it reads, at times, as a book about a deeply unpleasant young man. He knocks down his mother in a fight, perforating her eardrum with a premeditated punch. He kicks through doors. He demands money and threatens his family with knives. "We love you," they endlessly tell him.

But Myerson is not afraid to show her own dark side, too. Arranging an abortion for her sneering boy's quondam girlfriend, she tells the girl: "'All I want is for you to be OK.' It's not true. It's not all I want. All I want is for this to be over before she has time to change her mind." A mother protecting her cub is not always an appealing sight. And whether she knows it or not, transcribing mother-son rows verbatim only lends credence to her son's recent accusation that she is bonkers. "Yeah well. I didn't get to sleep till late," he says on the phone. "Why?" she says. "What were you doing?" Would it be facetious to say that this might drive anyone to drugs?

What this is also, however, is a campaigning book – and this may surprise those who have read that the crazy Myersons threw their son out on the street for smoking the odd spliff and having teenage tantrums. The psychiatrists and counsellors they consult tell them some scary things about skunk: that it is not the same as cannabis used to be; that its psychological effects are irreversible; that it is particularly damaging to developing teenage brains; that it is, says one, more dangerous than heroin. Their son – referred to throughout as "our boy" – insists that he is not an addict. One hopes he will use this opportunity to exercise the talent that everybody insists he has, and write a more convincing explanation of events.

Amid all the anger, the pain and the he said/she said of the Myersons' story, poor Mary Yelloly is rather lost. When he is shown the manuscript, the boy makes a number of factual corrections (and either does or doesn't give his permission to publish, depending on whom you believe), and tells his mother: "To be absolutely honest ... I wasn't all that interested in the stuff about the Mary Yelloly person." He's not the only one.

Whether or not the young man is an addict; whether his parents were right to expel him from their home; even whether it is fair to put a teenager's life into print: these are questions that will be addressed in news and columns and television discussion shows for some time to come. But if the question is whether a woman has a right to tell a story that is also, actually, her own – a book reviewer can only say yes. And add that anyone who reads it will struggle not to be profoundly moved.

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