It was a duty to the future, in fact, as the idea of an opposition that was legitimate and not simply bloody-minded was only just beginning to emerge. I have made Pitt say, ‘The King will do as he’s told.’ That’s a bit in the future too, as it was quite hard, until his health began to fail, to tell George III anything; he was far too conscientious and well informed for that. Certainly had he been less dutiful, less busy, he would have been less trouble to the politicians and perhaps to himself, as some at least of his mental torment can be put down to the frustration of a conscientious nature. ‘Cork too tight in the bottle,’ says Dundas. ‘The man has to break out somehow.’

Whether America played any part in causing his ‘breaking out’, it would be hard to say. He never wanted to be opposed, and to be contradicted as ordinary mortals were was, as Willis says, one of the lessons he had to learn. Certainly after his illness he was able to swallow America as he could not before, and he learned to be more sly, neatly reversing Pitt’s embargo on mentioning America by making Pitt promise that he in his turn would not mention, still less propose, Catholic emancipation.

KING  As for the future, Mr Pitt, you are not to disagree with me on anything, what? My mind is not strong enough to stand it.

PITT  (drily) I will do my duty, sir.

Whether or not George III was suffering from the metabolic disease porphyria remains an open question. In their book George III and the Mad Business (1969), Ida Macalpine and Richard Hunter argue convincingly for this retrospective diagnosis on the strength of the purple tinge the King’s urine took on while he was ill. Less convincingly, they trace the supposed incidence of the disease in other royals, nipping up and down George III’s family tree, attributing no end of assorted ailments to the same cause. So Mary Queen of Scots was said to have had the condition and her son James I; Queen Anne, George IV and even Frederick the Great. Although Hunter and Macalpine suggest that George IV’s brother, the Duke of Kent, was similarly affected, the condition does not seem to have been passed on to his daughter, Queen Victoria, so the (rather heartless) joke of the final caption probably has no substance.