One day in 1741, an enterprising Dutch sea captain called Douwemout van der Meer purchased an Indian, one-horned rhino called Clara. She had been captured in Assam as a calf and hand-reared by a director of the Dutch East India Company. As a party piece, she would walk sedately indoors, navigating the furniture, and eat from a dinner plate. The captain must have gazed in wonder as he imagined the riches the beast could bring him, if only he could get it across the seas to an astonished Europe. And so began the extraordinary travels of Clara.

Daft book, daft subject, you might think. But Clara was the 18th-century equivalent of a little green man from Mars. Many believed this fabulous beast was the legendary unicorn, or the Behemoth of the Bible. Indeed, before Clara's arrival, some Europeans only half acknowledged that such creatures existed. Pliny had said that they were aggressive, and hated elephants. Albrecht Durer had produced a woodcut of one in 1515, with an extra horn growing out of its back. That erroneous image remained in use for more than two centuries, until Clara lumbered on to the scene.

Reading this book, I rapidly became as fond of Clara as her owner no doubt was. She was perfectly suited to becoming an international celebrity, for she was placid and biddable and she travelled well. Her vital statistics were amazing. Six feet tall fully grown, 12 feet from nose to tail, 12 feet in girth and more than 5,000lbs in weight, Clara was a splendid specimen of the heaviest land animal in existence.

She was also lucky in having, in van der Meer, an owner who recognised that all Clara wanted to do was eat. Rhinos are herbivores. Clara could munch her way through 150lbs of vegetation a day, happily polishing off hay, grass, bread, oranges, even tobacco. Her other important requirement was moisturiser for that thick hide. In the absence of mud, the answer was fish oil, so Clara was often exhibited in fish markets. The smell must have been overpowering.

For 20 years, Clara and her Dutchman paraded around Europe in some style. Frederick the Great brought his court to see her. Maria Theresa, Holy Roman Empress, had a private viewing and promptly sent for her children. The king of Poland brought his ailing son; Casanova brought his latest mistress. Van der Meer refused to give Clara to the king of France (the price tag of 100,000 ecus which he set on her was too high, even for Louis XV), but accepted a holiday in the orangery of the Landgrave Frederick II of Hesse, where Clara spent one summer eating citrus fruit to her heart's content.

Van der Meer proved to have an eerily modern knack for PR. Handbills with Clara's picture would be fly-posted along their route. Commemorative posters and medallions went on sale. Clara "sat" for her portrait in marble, in Meissen porcelain, in oils; she became the star of Diderot and Jean d'Alembert's Encyclopedie and the Comte de Buffon's Histoire naturelle. French dandies copied her tail and horn in feathers and ribbons. A collection of fabulous clocks was modelled on her. The paintings of Clara, some of which are reproduced in Ridley's book, are fascinating. One image from Venice makes an explicit comparison between her and the masked harlots of the day. The rhinoceros, munching unconcernedly and depositing copious quantities of dung almost in the viewer's lap, is the clear winner.

Eventually Clara came a cropper, probably on mouldy bread, in London. Van der Meer returned home with wealth and titles, married at the age of 46, and was never heard of again.

In this enjoyable little book, Ridley shows how, in the age of Enlightenment, as observation clashed with classical authority, scholars flocked to Clara while the public came to gaze in simple awe on God's marvellous creation. Clara seems to have won the affections of everyone who saw her. This is a worthy tribute to a remarkable creature who should not be forgotten.

Edwina Currie's Diaries 1987-1992 are published by Time Warner Paperbacks