Lies to make the king's ears prick up

It tempts you to paraphrase Belloc: "Lola told such Dreadful Lies / It made one Gasp and Stretch one's Eyes." The life story of fantasist, bigamist and bogus "Spanish" dancer Lola Montez - in reality, Eliza Gilbert of Limerick - poses a problem for biographers, for all its colour and eventfulness. A straight retelling of the facts, entertaining though they are, still leaves us wondering about the inner self which informed these shenanigans.

Eliza spent her childhood being bundled about from India to Scotland to England. Born in 1820 and taken to India as a baby, she was separated from her widowed mother at the age of six and sent to Scotland to live with her new stepfather's family. A very beautiful child, she was also remarkable for her "vanity and lies", according to a family friend, Sir Jasper Nicolls, who was deputised to find her a school. When she eloped, aged 17, from the Ladies Boarding Academy in Bath with a Lieutenant James, 15 years her senior, Nicolls wrote in his journal, under the heading "Wretch Gilbert": "I am not a bad prophet as to the figure which young people will make in life ... she has started very badly." A few months later, he added, with relish: "a kind stepfather has lavished pounds 1,000 on [the] child's education & the dirty ungracious whelp has thrown it all away on the first man she met." This was to be a pattern: for every man she bewitched, she filled another - less gallant, or perhaps more clear-eyed - with revulsion.

In her memoirs Lola wrote that "The child sought only a protector but she found a master." Disillusion was swift, though she accompanied her husband back to India where mother and daughter, the vivacious Mrs Craigie and Mrs James, charmed the bored officers' wives. Her mother proved no support when she left James, however, telling her to return to Britain or get back to her husband. On the lengthy sea-journey to Southampton, the rebellious Eliza struck up a scandalous friendship with a young aristocrat, George Lennox, visiting his cabin alone and lingering with him on the poop deck when all the ladies had retired after dinner. So infuriated was the Captain that he barred Mrs James from his table. Surrounded by peeping eyes, the couple perhaps enjoyed putting on a show: the cabin door swung open rather too often to reveal Lennox lacing Eliza's stays or watching as she rolled up her stockings.

Once in London, Eliza resisted all attempts by her stepfather's family to remove her to Scotland. Instead, she shared a hotel room with Lennox, then moved to fashionable Half Moon St, a kept woman and striking new figure in society. But the affair faltered, and Eliza retreated to digs in the Hornsey Road. News of the scandal had filtered back to Lieutenant James and he wanted a divorce; the laws of the time left neither party free to remarry. At 19, she was a woman with a past, a near-untouchable in Victorian society. Her next move was spectacular: she decamped to Spain, where Eliza Gilbert James disappeared forever, and Lola Montez was born. Incredibly, this English-speaking, untrained dancer reinvented herself as a Spanish aristocrat's daughter with an imperious manner, a fondness for hand-rolled cigarettes and a repertoire of traditional dances.

At this point, Seymour's infatuation with his subject becomes clear: referring to her as "the fair Spaniard", he shows himself as willing as Lola's early, powerful protectors to enter the game. Lola was in fact a perfectly modern character, with her fluctuating identity, frequent switches of career - writer, lecturer, actress - her self-promotion, and her ability to check out of reality at will. By falling for her, Seymour absolves himself of the need to explain her.

There is a tiresome, strident quality to Lola's continuous and belligerent self-justification and lies. Unmasked almost immediately after her debut at Her Majesty's Theatre, she began what was to be a lifelong stream of outraged and mendacious correspondence to the newspapers: "I am a native of Seville ... when I was 10 years old [I] was sent to a Catholic lady of Bath, where I remained seven months ... From that period until 14th of April last ... I never set foot in this country and I never saw London before in my life." A rare outbreak of altruism shows Lola performing a benefit for a young playwright; shortly afterwards she left Britain for Europe, shrewd enough to realise that her slender talents, even coupled with a knack for scandal, could not support high ticket prices in one place for long.

On the road she attached herself to Liszt, then enjoying pop-star acclaim, met Wagner (who was not impressed) and, in a hilarious episode, flouted a pompous German princeling in his own court. A Berlin critic wrote: "Her dancing ... was no dancing at all but a physical invitation." The most talked- about number was the "Spider Dance", in which a village girl in a tight bodice discovers a poisonous spider in her voluminous skirts and attempts to shake, stamp and wiggle it free, finally crushing it beneath her feet. Clearly the performance was more or less saucy, according to the house. There were tales of Lola kicking off her garters into the pit, though a sour American critic much later in her career witnessed a more tawdry spectacle: "She flounces about like a stuck pig and clenches her short clothes, raising them nearly to her waist, while with a thin, scrawny leg, she keeps up a constant thumping upon the stage, as if she was in a slight spasm."

Despite her lack of Terpsichorean ability, all agreed on her beauty, which seems chiefly to have been a matter of dramatic colouring: clear skin, blue eyes, black hair. The photographs reproduced in this book show a sharp-featured Lola in later life, careworn and a little too cunning to be beautiful. The image on the title-page gives just a hint of her distinction: with short, swept-back hair, arching brows and large, febrile eyes, she looks rather like Fiona Shaw.

After many adventures, thrillingly recounted by Seymour (his description of the duel which killed her Parisian journalist lover is masterly), she wound up at the court of Ludwig I of Bavaria, where she and the deaf old king conversed in garbled Spanglish. For a courtesan she seems to have slept with the king very few times - Seymour tots them up like a jealous lover - and their correspondence is full of her fearful grumblings about pregnancy and Ludwig's keen interest in her menstrual periods.

Meanwhile, her insolent behaviour, flamboyant spending of the king's money and temper tantrums adjacent to mania had made her a loathed figure in Munich. This was 1848, the year revolution swept Europe, and the figure of Lola Montez came to be seen as an icon of political change; this was ironic, since she was always demanding that the king clamp down on his unruly subjects. After being run out of town on several occasions, she was finally forced to leave Bavaria when the king's troops could barely protect her from the mob. Ludwig abdicated with the fond hope of spending more time with Lola, now Countess of Landsfeld, but had to content himself with being sent pieces of flannel worn next to designated parts of her body, and letters which made his jajaro erect: "You can besar with great gusto and pleasure. My heart is yours, my cuno too, and all of me."

However, most of her letters were exclusively pecuniary; this, and the discovery of her constant affairs with soldiers and student agitators eventually disillusioned the king. She drifted back to London, still loudly demanding her royal pension while clumsily trying to hide her marriage to a wealthy young army officer, George Trafford Heald. The inconvenient longevity of Lieutenant James, and her own notoriety, landed her in court on a bigamy charge. Skipping to the continent, she soon drained Heald of money and her later years were one long world tour, taking in a final marriage of two months' duration to a journalist in San Francisco. Before dying of a stroke at 40 in New York, Lola seems finally to have freed herself from obsessive fantasising, living a quieter life, collecting exotic animals, studying the Bible and sharing the era's interest in spiritualism. It's a relief for the reader after all the screaming, gnashing, dagger- brandishing and whip-wielding of earlier chapters.

Seymour rarely strays into the "she must have felt ... it must have seemed" style of biography, and only occasionally risks an analysis of Lola's impenetrable states of mind. Like Wallerstein, one of Ludwig's ministers, he seems to regard her as having "absolutely no responsibility for her own acts". Seymour has dug up source material of extraordinary quality; all thanks to a huge win on the American TV game-show Jeopardy, which enabled him to become "an independent scholar" following in Lola's footsteps and designating himself, quaintly or camply, as her final victim.