Mrs Robinson's Disgrace: The Private Diary Of A Victorian Lady, By Kate Summerscale

A brilliant excavation of a scandalous personal history that left its imprint on family law.

Isabella Robinson, a middle-aged mother, wife and adulterer, lived and loved in Victorian Britain but she could just as easily have been a figment of a novelist's feverish imagination. Kate Summerscale herself makes a comparison between the subject of her latest social history and Gustave Flaubert's Madame Bovary; Isabella suffered from the same marital ennui, she had the same careering self-destructive streak and the overspill of sexual voracity that precipitated her infidelities. Even her name sounds like a smutty cross-reference to fictional bad women embroiled in fictional bad romances.

Yet every part of Summerscale story really happened. What's more, Isabella left a sensational imprint of her personal life on Britain's record of family law for future historians to mine. So Summerscale mines, richly.

Isabella came to national disgrace by carrying on with Edward Lane – a doctor many years her junior – and getting hauled into the newly-formed divorce courts when she was rumbled by her unloving husband. It is not the affair itself, nor the divorce, that gives her story its shock factor, but the fact that she described every scintilla of her passion in a diary discovered by Henry Robinson and presented in court as evidence.

The Observer refused to publish extracts of this "dangerous" material, which highlighted what the Victorians had taken great pains to deny: that women had sexual appetites too. Mrs Robinson is a seducer who hunts her prey, yet she is ultimately vulnerable – a woman who fears losing contact with her children after her separation, as was often the case in her era. In the end, she lost her social standing but her comeuppance was not the foregone conclusion that her husband (who was carrying on himself) had hoped for.

Despite its status as non-fiction, Summerscale's book is written with novelistic flourishes, perhaps because her hand is guided by Isabella's diary extracts, which become the real heart and voice of the book. Yet the diary also raises unanswerable questions over the veracity of Isabella's version of events. Summerscale suggests that her romantic imagination may have led her to exaggerate and embellish: "... tested against no external source, checked by no other perspective, the diary could conjure up a wished-for world, in which memories were coloured with desire." She got as much of an erotic kick from writing about the affair as from having it, Summerscale reckons. So how far did she really go with Edward, and to what extent did her documentation of reality collide with fantasy, we wonder, just as judge and jurors must have in 1858.

Summerscale has a gift for historical excavation and reconstruction. This book is every bit as captivating as her award-winning bestseller, The Suspicions Of Mr Whicher, which unpicked a heinous crime and exposed Victorian hypocrisies. This latest work takes us to another scandalous moment in the same era, and again draws our eye to the double standards by which polite society lived. As social history, Mrs Robinson's Disgrace highlights gender discrepancies in divorce laws at a time of new legislation. Summerscale's research also extends beyond Isabella's immediate world into the Victorian bohemia which lay on its fringes. Hers might have been a dull, middle-class existence but it collided with exciting alternative scenes. Charles Darwin and George Eliot floated around its edges; there were brushes with phrenologists, alienists, and she was constantly drawn to crowds that valued the imagination above her husband's colourless world of commerce.

As a human-interest story it is instantly gripping, with its first-hand account of sexual infidelity and its intimate replay of Isabella's likely emotions. She is a bold and brazen heroine, defying every stereotype of the Victorian wife. She pursues her lovers (moving on to other younger men after Edward) and seems to bring on the end to her loveless marriage by leaving her diary within arms-reach of her husband. For all her 19th century diarist's melodrama, she emerges as a thoroughly modern woman.