A leading expert on the era has uncovered evidence to show that the stories of Marie Antoinette's behaviour were cooked up by London criminals who blackmailed the French royal family.

Pamphlets

They printed the claims in pamphlets, then threatened to send them to France. Louis XVI paid them off in return for the destruction of the papers. But Simon Burrows of Leeds University has found that a fatally efficient bureaucrat filed copies in the Bastille, which were reprinted by the hundred thousand after the prison was stormed in 1789.

The revelations challenge the perceived wisdom that a tidal wave of libels about Marie Antoinette finally drove armed crowds on to the Paris streets - a story that is about to get another airing in Sofia Coppola's film about Marie Antoinette, which premieres in Britain next month. The epic has been marketed as the story of "the party which led to the Revolution", with the queen's naivety and folly sparking the violence. Instead, the senior lecturer at Leeds has discovered that a deal with the blackmailers held good until the fall of the Bastille in 1789, when violent revolution was well under way.

The theory is based on an unprecedented trawl of records left by French and British security agents, customs and excise - and revolutionaries whose circles were awash with rumour about secret royal porn.

Dr Burrows said: "There are letters between them saying 'Has anyone seen these pamphlets about the queen's filthy goings on?' They were desperate to get hold of them."

He argues that Versailles' combination of big cash payments and effective secret agents scooped up all the pamphlets, helped by the blackmailers themselves who were more interested in money than the guillotine. Dr Burrows said: "The blackmailers preferred to sell their silence to King Louis' government than to market their works openly, which was also dangerous and financially risky. The group in London was very well organised and knew how to keep on the right side of British law. They were in the clear so long as they were not going for people in England, or people whose reputation in England might be damaged." The reputation of the French monarchy in Britain was such that libel or blackmail could never have been an issue.

The eventual emergence of the obscene material, which was to blacken Marie Antoinette's name for two centuries, followed a final extraordinary twist in the tale. Bureaucrats at the court filed a representative copy of each pamphlet in the Bastille for possible use by government security agents. The explosive material fell into the hands of the mob which ransacked the prison.

Reprinted

Passed to revolutionary leaders, they were reprinted by the hundred thousand, including the infamous but almost certainly false claim that the queen suggested "let them eat cake" when told at her coronation that peasants were suffering a bread shortage.

"By this time, Marie Antoinette had become a hate figure for political reasons, castigated for lavish spending as France faced bankruptcy, and suspected, as an Austrian, of plotting to crush the revolution with her brother the Austrian emperor," said Dr Burrows. "The scandalous pamphlets found a ready market and their fame has continued ever since." The challenge to one of modern Europe's cherished stories is likely to be controversial, just as Coppola's film divided Cannes film festival critics who both booed and stood to applaud at the first showing.

Colourful historical figures such as Beaumarchais, author of The Marriage of Figaro and The Barber of Seville which Mozart later immortalised, claimed in memoirs to have been involved in suppressing pamphlets about the queen as early as the 1770s.

Dr Burrows said misspellings and reproduced printing errors proved that the mass circulation pamphlets, post-1789, came from the Bastille copies. The savagery of the lies about the queen culminated in the allegation at her trial that she had sexually abused her son, the heir to the throne. She refused to reply, saying: "Nature itself refuses to respond to such a charge laid against a mother."

Escape bid led to execution

Marie Antoinette was born in 1755 as Archduchess Maria Antonia von Habsburg - and that was the real reason why French revolutionaries came to hate and fear her.

Married at 14 to the future Louis XVI as part of a peace treaty, she was from France's traditional enemy Austria-Hungary. When she arrived for her wedding, she had to leave everything behind her, including her Austrian outfit, and cross naked inside a tent into France where she was re-dressed in French clothes. She made many enemies who spread false rumours about her extravagance and debauchery.

After an inept attempt to escape with Louis to Austria in 1791, she was confined to the Tuileries palace in Paris and later the Temple fortress. The king was guillotined in January 1793; she followed him in October. After years as a byword for aristocratic extravagance, her reputation is being re-examined by historians and emerging in a more sympathetic light.

· Blackmail, scandal and revolution; London's French libellistes 1758-92, by Simon Burrows, will be published on October 30 by Manchester University Press, £50