It was Gérard Lhéritier’s most amazing coup. The manuscript of Les 120 Journées de Sodome, the Marquis de Sade’s novel of sexual depravity and violence, had long been considered lost to French cultural heritage. Sade wrote it in 1785 while imprisoned in the Bastille for debauchery, by order of the king and at the request of his mother-in-law. He used his prison time fruitfully, to become a writer of plays, short stories and novels, and he composed The 120 Days of Sodom in tiny, meticulous characters on a strip made from 33 pieces of paper glued together. The scroll, which reached 12 metres in length, was rolled up and left hidden in his cell when he was evacuated just before the storming of the prison on July 14 1789.

Sade died in 1814, convinced his masterpiece had disappeared during the looting and demolition of the Bastille. But it had actually been found by one of the revolutionaries, who secretly sold it to a French aristocrat. It was subsequently bought by a German psychiatrist and then, in 1929, by Charles and Marie-Laure de Noailles, patrons of the Surrealist artists, who admired the violence of Sade’s writings. In 1982, in a Sadean twist, a publisher stole the scroll from their daughter, Nathalie, and sold it to a Swiss collector of erotica.