In this BMJ column Dalrymple critiques an interesting book – his own – having noticed an omission in his description of the behavior of a 19th Century murderer on the island of Jersey in The Policemen and the Brothel:
Nicolle was sentenced to death, but his advocate went to London to obtain a reprieve from the home secretary, who granted it on the grounds that Nicolle had in the past been mad. I quote now what I wrote about some of the evidence at his trial:According to [his landlady], his behaviour appeared strange and completely inexplicable on a number of occasions. For example she had seen him beating the walls with his fists until they bled . . . One night he slept in a box in his room instead of on his bed. [She] had never seen him drunk, and said that he was known . . . as Mad Nicolle.At the time of his madness he was learning his trade, which was that of—a hatter. Obviously, he was a mad hatter, but astonishingly and mortifyingly I missed this in my book. His symptoms, which fit no commonly seen pattern nowadays, were those of erethism caused by mercury poisoning. H A Waldron, in an article on the Mad Hatter in the BMJ in 1983 (BMJ 1983;287:1961, doi:10.1136/bmj.287.6409.1961), said the psychotic symptoms of erethism were excessive timidity, diffidence, increasing shyness, a desire to remain unobserved, and an explosive loss of temper when criticised.….How could I possibly have overlooked so obvious a diagnosis? But of course kind readers will point out that I have overlooked something in this article too.