In the mid-1960s Ida Macalpine and her son Richard Hunter, both psychiatrists and amateur historians, published a series of papers followed up by a bestselling book, George III and the Mad-Business, which argued that George III was not mad as was once thought. Instead, they claimed that George suffered from the inherited metabolic disease, acute intermittent porphyria, a diagnosis they later amended to the milder, though even rarer disorder, variegate porphyria. In spite of considerable criticism by porphyria experts based on their clinical experience, the claims of Macalpine and Hunter have been widely accepted by historians and were popularised by Alan Bennett's successful 1994 play and subsequent film, The Madness of King George.
There is no shortage of data concerning the four major episodes of illness endured by George III--in 1788-89, 1801, 1804 and 1810-20. These include around 100 volumes of medical notes and numerous diaries, letters and comments by contemporary courtiers, aides and politicians. The diaries of the author Fanny Burney, who spent five years at court in the 1780s as one of Queen Charlotte's ladies and who observed episodes of the king's madness first hand, are among this rich source of material. But to review all this evidence, especially the medical records, is a daunting task and it is one few historians have undertaken.
Having studied these records in detail, it is clear that Macalpine, who undertook the basic research for her son, was highly selective in reporting the signs and symptoms of the king's illness and there are far more plausible explanations for them. For example, the hoarseness Macalpine and Hunter claimed to be a feature of acute porphyria was attributed by the king's doctors to a head cold from which he recovered within a few days. In contrast, such symptoms in acute porphyria would frequently be terminal and even today are a serious matter, taking 12-18 months to resolve themselves.
Equally spurious as symptoms of porphyria are the six episodes between 1788-1819, of 'discoloured urine', so dramatically portrayed by Bennett in his play. Thus the famous episode of blue urine (itself not a feature of acute porphyria) was preceded by six reports of clear, normal, pale and yellow urine during six weeks of the same acute episode. The prescription of extract of gentian, a powerful bitter commonly administered as a digestive stimulant, three days before the report of the blue discolouration offers an explanation. These are just two examples of Macalpine and Hunter's misreporting of data. A morning in the British Library examining the relevant papers about Francis Willis who, with his sons, treated the king for madness, is time enough to expose the 'blue urine myth'.
The thesis is weakened further by the fact that acute porphyrias are inherited metabolic disorders, more common in female than male relatives. George III had 15 offspring and eight siblings and, had the king suffered from the disease, half of these should also have had the porphyric gene although they would not necessarily express the disorder: alcohol misuse and certain drugs are necessary triggers of the condition. Even so, around 10 to 20 per cent of those inheriting the abnormal gene will suffer from the disease. …