“SO HOW ARE you getting on with Florence Nightingale?” my husband inquired. “Well, she's arrived at Scutari so the story has perked up,” I replied. “But it has taken 200 weary pages to get her there.” And after Scutari, some 300 more: this is a long, long book.

The problem with Florence is that she wrote everything down and kept it, including a vast archive of drafts and corrections. Although she asked friends to destroy her correspondence on her death, she retained her copies, and their replies. We know therefore not only what she thought privately, but also how she changed her mind, what she issued for public consumption, and what was eventually published. She is, as Mark Bostridge admits, a biographer's nightmare.

To be fair to Florence, the long haul to Scutari must have felt like a trudge for her too; she reached it as an old maid of 37 after two decades battling her family for her freedom to train as a nurse. Florence came from a wealthy, landed family with a country estate next to Lord Palmerston's. From early years this intelligent, driven woman shrank from the genteel life of drawing rooms and afternoon drives, and the “slavery” of marriage in the days when wives were effectively chattels who belonged to their husbands. Offers of marriage she mulled over and turned down. Bostridge believes that she persuaded her father to give in by threatening suicide. Her private diaries show that she was frequently close to despair.

That was one battle; Scutari and the hellish state of the hospitals she found, and how she brought the death rate down, is another, and well worth reviving. The Lady with the Lamp was more than a fine nurse; she was an organiser beyond brilliance, and she bullied and cajoled the War Office to clean up, put up and shut up. It helped that she took with her more than £7,000 raised from readers of The Times who had been alerted to the shocking conditions of the casualties. Then, as now, it was easier for politicians to send soldiers to war than to provide for them properly away from the grim battlefield.

She was taken ill at Scutari with “Mediterranean fever”, which, it is now suggested, was brucellosis, caught from contaminated goat's milk. Its symptoms, which became chronic, included the fainting, nausea and back pain that afflicted her for many years. Yet this too was a battle won, for the invalid who strove so selflessly for others had found a way to avoid all distractions. She stayed in bed, turned down invitations, operated from the shadows like some latter-day Delphic oracle, and worked her acolytes almost to death in her service. There was a big dose of humbug in the sanctity. A daughter who accepted her father's money, she often said how she loathed the institution of the family; though she nursed her dying mother, her own health miraculously improved the moment her parents were dead, and she lived to be 90. The picture that emerges is not a pleasant one: Miss Nightingale was a bit of a monster.

Some admiration lingers. What she strove to create was a profession for women led by women, not under the control of doctors or anyone else. It had to be a “get down and dirty” job; Nightingale nurses scrubbed and bandaged whether they were ladies or charwomen. Her systems and hospital designs were copied worldwide. Service counted more than knowledge; the nurse should be aware of every little change in her patient's condition, and sitting with the patient was an essential part of her duties. We can applaud this approach: today's nurses might do better to spend less time in the lecture theatre and more at the bedside.

Nightingale is hard to pigeonhole today. A Christian with a hotline to God, yet a bigot who feared and hated Roman Catholicism; a feminist who disapproved of women doctors, feeling that they were trying too hard to be men; an independent-minded lady who operated only through powerful males, thus perpetuating the notion that women were not capable. One who officially shunned the limelight and thereby intensified her celebrity; the mistress of the media who knew to perfection how to win acclaim for her campaigns. A great humanitarian, who got her way with fits of temper and tyrannical bullying; who cared, as she herself admitted, for humanity in the round, but not in the particular.

Like Margaret Thatcher, who kept coming to mind, Florence Nightingale was a remarkable personality with durable achievements, but one who fails to command the affection of a more critical age.

Florence Nightingale: The Woman and her Legend by Mark Bostridge
Viking, £25 Buy the book

The Times Cheltenham Literature Festival: Mark Bostridge, Maura Buchanan and Christine Hallett discuss Florence Nightingale: October 10, 4pm
cheltenhamfestivals.com

Explore Books

• Book Extracts

• Book Reviews

• Books Group

• Audio Books

Times Recommends

• The 100 Best Books of the Decade
• The Times picks the 50 best paperbacks of 2009
• The conversation: James Ellroy