Sackvilles, Dorsets and Sackville-Wests (the twisting line of Knole's descent is complex and obscure) have been inhabiting this picturesque Kentish "calendar" house (it is said to have 365 rooms and 52 staircases) since an Elizabethan Sackville drew up a 52-page will to devise its descent, throughout the centuries, from "heir male to heir male". No amount of tomboyish behaviour by Vita Sackville-West, the house's most ardent devotee, could shake Knole free of that masculine stranglehold, and no better evidence of the vicious side of male ownership appears in Inheritance than the account of Vita's uncle (the successor to her father) having the word "Knole" effaced from a replacement garden key, thereby rubbing out Sackville-West's last link to her childhood home.

"A rotten lot, and nearly all stark staring mad" was how Vita, always preferring the vast and secretive old house to its owners, described her ancestors. Lord Derby, a family friend, put matters more discreetly, murmuring to the pages of his private diary that there was something "not quite consistent with sanity in the continual and ceaseless quarrels which arise in the family".

Knole was destined to cause heartache, not only because of the terms of an Elizabethan Sackville's will, but also because, while remodelling the original 15th-century building into a giant show house within easy reach of London, the court and valuable patronage, Thomas Sackville neglected to provide a more solid basis for its future maintenance. A thousand acres of Kentish meadowland may have looked delightful, but such uncommercial acreage could never generate enough income to support a palace. Thus, down the decades, as meadows were transformed into parkland, the ravishing beech avenues planted by one Sackville would be chopped down by an heir who needed to convert timber into cash  unless, that is, a suitably grand heiress turned up to save the day.

This history of Knole is peppered (intermittently) with lively characters. Take the slumbrous-eyed and pink-cheeked third Duke of Dorset  a possible model for the Scarlet Pimpernel  whose massive art collection enriched the house, and whose favourite mistress was a sweet-natured Italian dancer. La Baccelli enlivened Knole; until, that is, a disapproving  and, of necessity, very rich  duchess moved in. The dancer promptly vanished, while her portrait by Gainsborough was dispatched to the attic, together with her remarkably lifelike statue, nude upon a cushion, prone and seductive.

Few Sackvilles sound so agreeable as the Duke of Dorset's pretty dancer. Knole's latest historian, nevertheless, shares Vita Sackville-West's affection for 17th-century Edward, a privy councillor and Lord Chamberlain who ended his days, by his own account, "a poore unsuccessfull Cavalier who died in debt, a sad recluse". Reclusiveness, harmless in Edward's case, reached an unpleasant extreme in late Victorian times, when Mortimer Sackville, enraged by an increasingly adventurous and intrusive public, barred his home and grounds to visitors and, invaded subsequently by an angry mob, summoned to his defence no less than a third of Kent's constabulary. Suing the rabble's ringleaders in a well-publicised court case, Lord Sackville won, with damages of just £5. This real-life version of Oscar Wilde's selfish giant died three years later, childless, friendless, and convinced his servants were trying to poison his porridge.

It is here, around the halfway mark in Inheritance, that life starts to get interesting. Scandal rears its head with the arrival at Knole, in 1888, of nasty Mortimer's fraternal successor, Lionel, together with a bewitching half-Spanish daughter, Victoria, who managed to preserve her own place at the house by marrying yet another Lionel, her cousin (have I mentioned that the Sackvilles' genealogy can become confusing?). Victoria produced, however, not the requisite "heir and spare" but a solitary girl  Vita  before helping her husband to fight off the claims laid to Knole by her own (illegitimate) brother, Henri. One sensational court case succeeded another, much to the joy of the press and its ravenous readers. In 1912, just three years after seeing off Henri (who subsequently killed himself), a tearful Lady Sackville found herself back in the dock, defending her honour for accepting £150,000 (along with a superb furniture collection) from the late Sir John Scott, an admirer whose massive fortune was matched by his 25-stone girth. Scott's children had not relished the speed with which Lady Sackville had invited dealers in to value their father's antiques. They also questioned their father's earlier gift to the ever-receptive Sackvilles of a splendid house in Mayfair. The jury, rejecting the Scotts' allegations of coercion and fraud, took less interest in the evidence than in the touching testimony of young Vita (hailed by the press as "Kidlet") and the transcendent beauty of Lady Sackville.

The National Trust, since 1946, has shared the house with its ancestral owners in what seems to be a fairly harmonious arrangement. If naughty tales do exist about what is often a tricky marriage between public obligation and private tradition, Robert Sackville-West isn't telling. What he offers readers instead is a graceful and thoroughly researched history that freely acknowledges, without attempt at rivalry, its debt to a glorious predecessor: Vita Sackville-West's intense, romantic hymn to the home that she unappeasably adored.

Miranda Seymour's books include In My Father's House: Elegy for an Obsessive Love (Pocket Books).