A Profound Secret by Josceline Dimbleby

A Victorian tableau of passion and repression

At the recent Royal Academy show of Lord Lloyd-Webber's Victorian collection was a haunting portrait of Amy Gaskell by Edward Burne-Jones, with luminous whiteness of face and hands against a dark dress and background. Aged 19, and soon to be married, Amy was the daughter of May Gaskell, the artist's latest romantic confidante, and the portrait a token of their attachment.

At the recent Royal Academy show of Lord Lloyd-Webber's Victorian collection was a haunting portrait of Amy Gaskell by Edward Burne-Jones, with luminous whiteness of face and hands against a dark dress and background. Aged 19, and soon to be married, Amy was the daughter of May Gaskell, the artist's latest romantic confidante, and the portrait a token of their attachment.

A chance meeting with Lloyd Webber led the food and travel writer Josceline Dimbleby on a quest, for she is May's great-grand-daughter. Large, enigmatic photos of Amy standing in a punt on a glassy lake before the ancestral home fill family albums. This enchanting book is the fruit of her discoveries.

Not absolute discoveries, always: Burne-Jones's letters to May were quoted in Penelope Fitzgerald's 1975 biography. They are, however, given full value here as the lasting joy of May's life. "I hold all the week free for the chances you give me - for though my love is celestial my silly eyes hunger to look at you," wrote the 60-year-old artist to 40-year-old May. "I lie in a meadow tonight with my head in your hands safe and content."

Burne-Jones burnt May's letters, which augments the sense of intimacy. But also revealed here are May's letters to Lord Milner, another devoted admirer, which show just how unhappy she was with Captain Henry Gaskell, a cold, depressive bully. These traits Dimbleby traces in all the male Gaskells, along with a prodigious beak.

Gaskell, one infers, refused May an honourable separation, and she accepted her duty. To Burne-Jones, beauty and misery were irresistible; his love letters, with their tender fantasies of escape, evidently assuaged her despair. She read and re-read them all her long life.

A Profound Secret is threaded on May's life, but its heart is the enigmatic Amy, a bewitching young woman who followed her mother into a loveless military marriage (stop, stop! one wants to shout). Amy had real talent: her panoramic photos, often staging herself in Lady of Shalott roles, look worth some study. Selfishly unhappy, she wandered the world drawing men to her beauty and misery.

Frank Rose yearned for eight years before proposing to Amy's horsey little sister. Then Amy's husband died. She hastened home from Ceylon, hardly for the funeral, but perhaps for Frank - who refused his fiancée's offer to release him - or to secure an inheritance. Something happened; overnight, Amy was dead, surely of a sleeping-draught overdose. What a film this would make.

Amy's inner life eludes her great-niece, giving the narrative a delicious poignancy. For Dimbleby foregrounds the biographical romance, with its emotional and uncanny moments, as when she unwraps the paintbrushes Burne-Jones gave to May when May's portrait was completed, or bumps into an unknown relative in the Ashmolean print room. Then, the quest is confirmed, as she uncovers the clues May left to "those who come after".

Anecdotes also abound. Queen Mary's contributions to the War Hospital Library, founded by May, were largely bulb catalogues and treatises on manuring. Captain Rose's posthumous child was called Briar, in honour of Burne-Jones's famous work. But, said her mother, let's hope she doesn't marry Mr Pipe.

Jan Marsh's biography of DG Rossetti is published by Weidenfeld & Nicolson