Sissinghurst: An unfinished history, By Adam Nicolson

Most of us do not inherit castles. We are probably lucky. There can be more grief than glory in such a legacy, especially when the castle, however much it feels as if it's yours, is in fact owned by the National Trust.

Faced by heavy death duties, the heirs to great estates often do as Nigel Nicolson, Adam's father, did and hand the place over to the Trust, with the proviso that they and their heirs may continue to live there. From 1962, when that happened at Sissinghurst, until his death in 2004, Nigel stayed on.

When the lot fell upon Adam, his troubles began. He gives a very funny account of a day in June 2006 when he attended a meeting in London of the Trust's "donor families". Besides the woman with, he considers, the most wonderful name in England, Mrs Horneyold-Strickland, it was peopled by men in soft, well-cut suits; by women in sub-Chanel ensembles and giant diamonds; by scions of many of the grand aristocratic families of the land. It brings to his mind the Congress of Vienna, or Agincourt. All they can do is grumble, these dinosaur donors with the illusion of significance but not the substance of power. Adam comes away with a realistic appreciation of his position: if you can't be a Rothschild, he concludes, it's better to be a penniless Nicolson, happy to accept whatever might be on offer. But life isn't always that simple.

This book is a deft intertwining of two narratives. The first is extremely personal. With great panache it begins, à la Daphne du Maurier, "I have often dreamt of Sissinghurst on fire..." The pronoun "I" occurs 15 times on the first page, setting the tone for the story of his idyllic early childhood when his parents were still together, his mother cooking warm, comforting meals and his father taking him exploring the estate and beyond, on foot or bicycle, sometimes in a canoe. He learned the lie of the land, its woods and streams, its fields, hop-gardens and barns in minute and loving detail. The yearning nostalgia of Siegfried Sassoon – or even of Hardy – begins to replace du Maurier in the reader's referential memory.

The second is a far larger history, embracing the Weald of Kent from the dawn of time until a couple of months ago. There is little written evidence of the early days, but that does not deter a writer of Nicolson's calibre. He marches on, through the ancient hursts (forests), dens (pig-pastures) and hams (flat lands near a river), using the etymology of place-names to tell their history. Sissinghurst may well mean a wood where Saxons settled, as opposed to nearby Angley, where the other half lived, in a glade. It's heady, seductive stuff, though you might find it hard to believe that the neighbouring village of Wilsley, once called Wivelsleah, was so named because it had been "the woodland glade of a man thought to be a weevil".

Back at the ranch, he pores over the records, and he battles with the Trust. At first they are frosty about his great idea: that the land around the castle should once again become a useful and productive mixed farm, providing organic food for the restaurant and reinvigorating the soil. I can think of nobody today writing more persuasively about the value of this way of life. But though he cherishes the dream, he also acknowledges that he wants to make his mark: "I did not simply want to be the receiving son."

Many a son has made his mark here. Sissinghurst has been a Tudor estate, a Renaissance palace, an exclusive deer-park, a grisly prison for captured 18th-century French sailors and a ruin. When Adam's grandparents, Harold Nicolson and Vita Sackville-West, bought it, they planted a garden and invited the public in, at sixpence a head. The garden remains famously lovely, but the surrounding estate has become, in Adam's view, tired and underproductive. All this might be about to change. His persistence seems to be paying off and the Trust has given him a cautious and encumbered blessing to implement a version of his scheme. It remains to be seen whether or not he can pull it off.