Book of a lifetime: Dusty Answer, By Rosamond Lehmann

Some books read early stay with you forever, that first dazzled encounter making such an impression that the texture of your life becomes part of the narrative. So, for me, 'Our Island Story' is about being nine and lying on a wall beside a swimming pool: a warm Pepsi with a straw in it, the smell of chlorine and pine trees.

'The Wonderful Story of Henry Sugar' is about bolting a cheddar and Branston sandwich in the dining hall of primary school, itching to finish the last few pages before afternoon lessons. There's a family day out on a Somerset steam train when I was 12: people trying to interest me in things passing, and then shrugging and giving up, saying, "Well, that's Rebecca for you."

Those pin-sharp moments of discovery… how to choose one book from a lifetime of reading? Actually, it's easy. I know exactly where I was when I first encountered Rosamond Lehmann's 'Dusty Answer': at boarding school, in the great creaking Arts and Crafts library (part barn, part ship; one of the few places I felt safe). More precisely, I was upstairs in the fiction bay when one of the Murray sisters recommended it. It was an old cloth-bound edition, possibly blue or pale green. I think I was 15. There is no better age to read 'Dusty Answer'.

I opened it and fell into it, as you fall into a fever. We were studying Keats at the time, and I recognised in Lehmann's novel (published in 1927, when she was 26) some Keatsian echoes: not only the heady overwhelming gorgeousness of the language, but also the sense that life is about beauty and loss.

This is the story of Judith Earle, a serious lonely girl growing up in a house by the river, in love with a family of cousins who come and go in the house next door. Charlie, nervy, golden, "as beautiful as a prince"; cool Mariella, with her "mermaid's eyes", who delights in thunderstorms; fierce awkward Julian; Martin, who loves Judith doggedly, and is therefore of little interest to her; and the elusive Roddy, full of secrets, "with a smile that you watched for because it was not like anyone else's".

Lehmann's story is both universal and deliciously particular, like all the best coming-of-age stories. No one has written more brilliantly about having one's heart broken, about despair and longing, humiliation and hope: all the wretched thrilling chaos that accompanies growing up. Finding it at 15 felt a little like stumbling upon magic. Miraculously, all these years and re-readings later, it still has that effect on me.

Harriet Lane's 'Alys, Always' is published in paperback by Phoenix