Cavalier: a tale of chivalry, passion and great houses, by Lucy Worsley

It is easy to see what Lucy Worsley is trying to do in Cavalier. She has written a thesis for a PhD which is chock full of interesting nuggets. The idea has come to her that she should serve them up in a book. The tension lies between her abilities as an intellectual, and her creativity as a narrator. While there is no doubt that the academic Worsley knows her facts – Cavalier teems with interesting minutiae about a 17th-century aristocrat's household – the author Worsley falls short, finding the weaving together of a cohesive narrative beyond her.

This is a shame, because her subject, William Cavendish, is one of the more colourful characters of the 17th-century aristocracy. Highly sexed, massively rich and with a middling talent for verse, he delighted in erecting large houses and in composing smutty ditties for whichever female member of staff had most recently caught his eye. He fancied himself as a playwright, too, but Samuel Pepys wrote that one of his offerings, The Humorous Lovers, was "the most ridiculous thing that ever was wrote".

We first meet Cavendish in a deathbed scene, at the conclusion of which he inherits much on the passing of his father. We follow him through the ensuing eight chapters – "A Masque", "A Battle", "A Bedchamber Conversation" – which vary in ambition, and in the directness of their connection with Cavendish, before our flawed hero breathes his last. Each section of the book is episodic: Worsley presents us with a snapshot of the life that magnates such as Cavendish endured, as much as enjoyed: in "A Royal Palace", for instance, we share his agony at the expense of hosting royal visitors at Welbeck, while understanding the sense of favour that this uniquely ruinous set of guests imparted.

Worsley's strength is her sense of period, and her ability to bring people to life. It is almost as if she knows each of the army of servants that attended the Cavendishes, thanks to her forensic knowledge of the family's archives. As we learn of the preparations of a banquet for Charles I, she names the head cooks: "The Yateses are preparing to roast pigeons, pheasants, gulls, larks, redshanks, herons and bitterns in an orgy of the ornithological cuisine so loved in the 17th and 18th centuries." The author frequently has a neat turn of phrase.

More laboured is her use of the "necessary woman", that unfortunate retainer whose job it was to deal with her master's chamber pot each morning. It seems likely that her path from the bedchamber to the hills below the castle would have been as quick as possible. However, Worsley employs her as a director might a camera on an endless tracking shot as a way of throwing light on her fellow workers' toils in what might be seen as the engine room of the Big House. Given her load, it is unlikely she would have been that welcome among her co-workers; but Worsley has her spending a long time in the kitchens, the stench of her master's "night soil" apparently offending nobody.

Another unsuccessful device is the author's attempt to impart a sense of unquestionable authority by stating a case too strongly. She says of her hero: "William's father and William himself belong to the last generations to appreciate art containing 'some witty devise expressed with cunning workmanship, something obscure to be perceived at the first, whereby, when with further consideration it is understood, it may the greater delight the beholder'." Really? It is a broad-brush statement that is utterly wrong. James "Athenian" Stuart, Peter Carl Fabergé and Anselm Kiefer are among the thousands who have subsequently delighted their patrons with their multi-layered creations.

Similarly the case is not made to support Worsley's conclusion that William's wife, Margaret, "is truly one of the 17th century's most remarkable women". On this book's evidence, the duchess was a wonderfully loyal wife, who wrote over-generously of her husband's gifts. That she was an aristocratic female author in the second half of the 17th century makes her noteworthy, but there is no evidence of greatness.

Meanwhile, it is not clear that the title of the book has been thought through. "Cavalier" was a term of contempt hurled at Charles I's horsemen by Parliament's propagandists. The Royalists chose to interpret the word as emphasising their commitment to serve the King bravely, while mounted. Although Cavendish enjoyed almost vice-regal status in the North of England because of his local influence, his military career was short-lived and ignominious: he was one of the defeated Royalist commanders at Marston Moor in 1644. After this serious reverse, he fled overseas because he was afraid of being laughed at by his fellow courtiers.

William Cavendish was an engaging eccentric. However, his achievements are too insubstantial to take the load of Lucy Worsley's research into the workings of his household. This book shows off the fruits of an admirable thesis, but unfortunately the journey from academia to narration, crucial to the project's success, has not been achieved.

Charles Spencer is the author of 'Prince Rupert: the Last Cavalier' (Weidenfeld £20)