King George III is undoubtedly the most famous ‘mad’ patient in British history. The most dramatic and consequential episode of his illness set in during October 1788 and lasted until late February 1789. These were five months during which the English court, the political class, and the general public were ceaselessly agitated by conflicting reports and predictions. George’s frenzy or derangement, whatever it was, and however it was diagnosed, had consequences for the state and for the constitution. Since the king was unable to carry out his official duties, and it was thought possible he would never recover, his illness occasioned an extended and fierce struggle for power between the Tory Party, under William Pitt, long supported by the king, and the opposition Whigs, led by Charles Fox and patronised by the king’s eldest son, the Prince of Wales.