A new book reveals fresh evidence recasting the villain of the Bounty as the famous saga's true hero. A poor boy made good, he was smeared by the mutineers' aristocratic familes.

It is the stuff of legend: William Bligh, brutal, sadistic captain of the Bounty, suffering the righteous fate of a tyrant when he is toppled by rebel with a cause Fletcher Christian and his plucky mutineers.

But a very different account, revealed for the first time today, shows how Bligh has been wronged by history: how he was in fact a British war hero more deserving of a knighthood than lasting infamy, who treated his men on the Bounty no worse, and in many cases better, than other seafarers of his day.

His only crime was to have worked his way to the top by the age of 34, and so condemned himself to the snobbery of the British class system.

Christian, far from the downtrodden innocent, was a bankrupt aristocrat who appears to have acted out of spite and wounded pride. As a 'gentleman' he was affronted by Bligh's candid language, and may never have recovered from the indignity of having had to borrow money from his nemesis.

Bligh's fate as villain of the piece was sealed by spin: a concerted smear campaign by the well-connected families of Christian and his associates, ensuring that over centuries of storytelling, culminating in Hollywood, the tale would be embellished to leave Bligh on the wrong end of one of history's great miscarriages of justice.

The radical revision is presented in an authoritative new book, The Bounty: The True Story of the Mutiny on the Bounty, by Caroline Alexander. Not content with naval records that have formed the basis of previous studies, the author spent three years studying wills, private letters, court reports and other documents, turning up vital new evidence.

'I hope this establishes Bligh as the hero and not the villain,' Alexander said. 'The origin of it all is a nasty class snobbery. Bligh is accused of not being a "gentleman" - and only a gentleman can understand why Fletcher Christian had to do what he did. That was the basic argument.'

The sequence of events has become familiar through countless books and films starring the likes of Charles Laughton, Trevor Howard and Anthony Hopkins as Bligh.

In 1789, as the Bounty sailed away from Tahiti, 24-year-old master's mate Fletcher Christian led the mutiny, casting Lieutenant William Bligh, the ship's captain, and 18 loyalists adrift in a 23ft launch with rations for five days. Christian and his followers began a restless exile while Bligh survived a 48-day, 3,618-mile voyage across the Pacific.

The mutiny erupted after Bligh clashed with Christian over the seemingly mundane issue of missing coconuts. Alexander said: 'Bligh clearly accused Christian of being a thief or a scoundrel. Later supporters of Christian tried to make out that was sufficient for the mutiny. How could a man of honour be expected to live having heard such incredible words?

'It was only later, when times changed, this no longer washed in the same way. It was then that stories started creeping in about Bligh threatening Christian with corporal chastisement, and then flogging Christian, and then you jump into the Hollywood period.'

Alexander said the propaganda offensive to blacken Bligh's name was launched in his own lifetime. 'Christian's brother Edward, a lawyer, was mounting the campaign, interviewing everybody he could get his hands on who'd been on the Bounty, and using the press to great effect. He was like a spin doctor.'

The book, published next month by HarperCollins, relates how the Royal Navy's effort to bring the mutineers to justice was complicated by the political, legal and social influences exerted to defend the reputations of Christian and one of his 'gentleman' colleagues. The author continued: 'The families of Christian and Peter Heywood [who was later pardoned] could virtually trace their ancestors back to Domesday and were all bankrupt through totally irresponsible management of their family finances.'

Alexander argues that, while flawed and short-tempered, Bligh compared favourably with his contemporaries. 'He served with great distinction in two important battles in the Napoleonic Wars; others were being handed titles for taking part in one,' she said.

The book looks certain to outrage Christian's descendants. Glynn Christian, the mutineer's great-great-great-great-grandson, once wrote to a newspaper: 'There is nothing new to say about Bounty, Bligh or Christian ... William Bligh was a magnificent navigator and a truly awful man ... just as Fletcher Christian was a wicked mutineer and an interesting pioneer of democracy and female emancipation.'