This horrifying and engrossing book could scarcely be improved upon. In this age of HRHs Harry, William and Kate-led openness about our mental health, I declare an interest: diagnosed as cyclothymic, and having known more than two attacks of depression and hypomania in the past 30 years, I would have been disqualified from passage as an emigrant to New York by the 1907 US Immigration Act, which prohibited ‘All idiots, imbeciles, feeble-minded persons, epileptics, insane persons and persons who have been insane within five years previous….