BOOK REVIEW / A pampered menagerie: Aristocrats - Stella Tillyard: Chatto & Windus pounds 20

IN HEATED catacombs beneath Goodwood House lived the pampered menagerie of the second Duke of Richmond. There were tigers, bears, wolves, leopards and an armadillo, to name but a few. When a favourite lioness died, her owner built her a magnificent marble tomb in his park, where her bones still lie among the trees. His friend Lord Hervey remarked that the erotic behaviour of Richmond's animals was 'an allegorical epitome of the whole matrimonial world'. He could have said the same of the four daughters of the house.

This Duke was a grandson of Charles II and his mistress Louise de Keroualle. His daughters, the Lennox sisters, are the subject of this fascinating book. All taint of bastardy had disappeared by the time they were born. They were indeed aristocrats and, as such, expected to marry well and to found further great dynasties. Mostly, they did just that. Their descendants were Napier generals, Fox politicians and Fitzgerald patriots, but they are interesting on their own merits, as dynamic individuals, and affectionate and literate sisters.

All their lives they wrote to each other virtually daily. If the telephone had been invented, their bills would have been cosmic. As it was, their letters bring the 18th century right up to date. 'Since you love a folio sheet of paper, dear siss,' wrote Caroline to Emily in 1759, 'you shall have one. I'm sure I shall fill it, for once I get into a talking or a writing way, there is no end of me.'

Caroline was, in a way, the most interesting. She carried all the burden of being the oldest: serious, learned and responsible. Yet she was also fascinated by decadence and seduced by the attentions of Henry Fox, a short, stout, hairy genius only four years younger than her father, with whom she eloped. Their home, Holland House, though kept freezing cold, became an extension of London coffee houses, frequented by all the big political and artistic figures of the day. She was a great one for medical theories and owned endless books on the subject, from Pringle's Diseases of the Army to Cadogan on gout. She dosed her sons on oxymel of squills and ground woodlice, but they survived to do the grand tour, picking up, as Stella Tillyard says with a typical flourish, 'polish, women and gambling debts'.

Emily was the glamorous, extravagant one. Painting her, Joshua Reynolds remarked that she had 'a sweetness of expression hard for a painter to capture'. For her doting husband, the Earl of Kildare, Emily and expenditure were coupled together. The more she spent, the more excited he became. The result was huge debts and a family so large that she sometimes failed to recognise her children. Arriving home after a trip to London 'a dear little child runs in to me and puts its arms round my neck. Who should it be but dear Henry] . . . I wonder I did not know him.'

Her husband considered sex to be 'necessary to a woman's health and happiness'. This observation drew a retort from Caroline: 'It's abominably indelicate and I don't believe a word of it. I'm sure one sees many an old virgin mighty well and comfortable.' But so vital was it to Emily that she ran off with her children's tutor and presented him with the last four of her 22 offspring, managing to pick up a house and some cash on the way and - miraculously - to retain a virtuous reputation.

Louisa was childless, though married to the richest man in Ireland, an affable chap whom she thought of as her flea: 'He hopped about, guileless and full of muscle.' Discreet and sympathetic, she was everybody's favourite. Sarah, the youngest to survive infancy, was dandled by George II, pursued by George III, married to a useless fellow called Bunbury, carried off by another lover and only pinned down when she was 36 by George Napier, 'the most perfect-made man ever'. Then she became a devoted wife, and mother to eight little Napiers. When her husband died, she wrote: 'I have lost him who made me like this world. It is now a dreary expanse.' Then she managed to acquire a pension from the King in recognition of his own youthful passion.

This book is an extraordinary achievement. Making light of an Everest of contemporary documents, including household accounts, diaries, library lists, autopsies, building-plans and, of course, letters, Tillyard takes her reader straight into the lives of these women, so accessible in their emotions, so delightful in their intimacy. They gossip, they argue, they boast, they confide, they rejoice, they mourn, they grow old together. The rich may be different, the past another country, but sisterhood like this endures for ever.