The man on the wheel started bellowing, cursing and swearing in his agony. The drunk raised his head towards the scaffold, took offence at what was being said, and called out: ‘There’s no need for rudeness, even if they are breaking you on a wheel.’ This quip was much admired in aristocratic circles.”

So far as the two Queens were concerned, Rohan’s chances were ruined for ever by the indiscretion of Mme du Barry. At the time Prussia and Russia had just carved Poland up between them. Maria Theresa, while strongly condemning their actions, could do nothing about them and demanded a share for Austria. Rohan, who had a justified reputation among his contemporaries as a wit, took the occasion to write to the Duc d’Aiguillon: “Maria Theresa holds a handkerchief in one hand to wipe away her tears, and a sword in the other, hoping to becoming the third partner in the spoils.” D’Aiguillon sent the letter to Du Barry, who took great delight in reading it aloud to her guests over dinner, and they were quick to repeat the contents to Marie-Antoinette the following day.

But while the blundering ambassador slandered Vienna in Versailles, he took every opportunity to slander Versailles in Vienna. Stories that he was spreading about Marie-Antoinette reached Maria Theresa’s ear. Her maternal heart was so aggrieved that she sent Baron Neni to find out what truth there was in them, and the Baron established that Rohan’s source was baseless chatter emanating from the Du Barry-Marsan-Guéménée clique, who so despised the young Queen.

So it was perfectly understandable that Marie-Antoinette too should do everything in her power to have the doubly indiscreet ambassador brought home. But Rohan was protected by his powerful aunts, and while Louis XV was alive, and Mme du Barry remained who she was, it was impossible to remove him.

In April 1774 Louis XV contracted smallpox. Du Barry took herself off to Rueil, and only his daughters remained at his bedside. The Court continued at Versailles, waiting impatiently for the candle burning in his window to signal that his appalling death struggles were over, so they could then leave the infected Palace and withdraw to Choisy. Finally, on 10th May 1774, the flame was extinguished.

The King’s corpse lay there, slowly breaking open. It was already half-decayed, and a hideous stench was pouring from it. The Duc de Villequier, Premier Gentilhomme de la Chambre, called on the surgeon, Andouillé, to carry out his traditional office and apply balsam to the body. Andouillé knew that it would inevitably mean catching the infection himself, and replied: “Very good; but it is your duty, Your Excellency, to hold the head while I do it.” Villequier dispensed with the embalming.

“The Dauphin was with the Dauphine,” records Mme Campan. “They were awaiting news of Louis’s death together. A dreadful noise, absolument like thunder, was heard in the outer apartment above them. It was the crowd of courtiers who were deserting the dead sovereign’s antechamber, to come and do homage to the new power of Louis XVI. This extraordinary tumult informed Marie-Antoinette and her husband that they were called to the throne; and, by a spontaneous movement, which deeply affected those around them, they threw themselves on their knees; both, pouring forth a flood of tears, exclaimed: “O God, guide us and protect us. We are too young to reign.”

Thus Marie-Antoinette ascended the French throne. That same year Rohan was recalled from Vienna.

His departure was not very dignified. Maria Theresa refused to receive him before he left. Rohan sent his friends a portrait of himself engraved on a thin layer of ivory, and such was his popularity that it was much copied onto rings and encircled with pearls and diamonds. Even Chancellor Kaunitz wore one, to the Empress’ intense annoyance.

He was replaced as ambassador to Vienna by Baron Breteuil. Rohan could not forgive the man for succeeding him, and Breteuil was even less forgiving of the hostile treatment he received. When the time came, his loathing would be fatal for Rohan.

Still greater discomfiture awaited the ex-envoy in France. The King received him coldly; the Queen refused even to see him. She simply sent word that he should forward the letter he had brought her from Maria Theresa. Rohan was in disgrace.

In the Ancien Régime, to be disgraced was not necessarily fatal in a material sense. There was no chance of his starving to death. In fact, during his time in this supposed wilderness he achieved one enviable distinction.