[Richard Dadd] remained convinced that he was on a mission to battle the devil, who could take many forms, including that of Dadd senior, and that the artist formerly known as Richard Dadd was in fact descended from Osiris. (location 509)
Broadmoor Revealed: Victorian Crime and the Lunatic Asylum is a short e-book, available free from Amazon and Smashwords, compiled by the senior archivist at the Berkshire Record Office. Mark Stevens has picked out some of the most intriguing case histories from the vast archive of medical records and case notes.
There are chapters on infamous inmates such as 'Fairy Feller' artist Richard Dadd; William Chester Minor (a.k.a. 'the Surgeon of Crowthorne', and a prolific contributor to the Oxford English Dictionary); and Edward Oxford, who attempted the assassination of Queen Victoria. Stevens also describes the histories of some of the female inmates; and there's a chapter devoted to escape attempts, successful and otherwise.
There are some fascinating details amid the accounts of daily life in the asylum; croquet matches on the lawn, employment for the working-class inmates, and Richard Dadd's distrust of chess pieces 'due to the antiquity of the game'. (Sometimes Dadd's behaviour reminds me of a character in a Tim Powers novel.)
The most interesting aspect of the book, for me, was its insight into Victorian attitudes to insanity. "[Moral insanity] was a disease free of delusions, but where the mind was unable to think and behave properly as it should. Although it did not fit the modern term of psychopath, itself a rather overworked word, it is perhaps the nearest to it that the Victorians acknowledged." (location 221). The Victorians didn't regard the mentally ill as exhibits or, necessarily, threats; Broadmoor was not a prison but a refuge.
That said, approximately a third of the inmates at any one time were 'time', meaning that they were serving a sentence for a crime. Their reward for good behaviour was a return to the prison system. The 'pleasure' inmates, who had been declared insane and were detained 'at Her Majesty's pleasure', could look forward to an enlightened and humane regime of adequate meals, a roof over their heads and some meaningful occupation -- unless their condition improved sufficiently for them to be released. Given those parameters, and the lack of effective medical treatments for 'moral insanity' and 'lesions of the will', it's amazing that anyone was ever discharged.