Nowadays a pathologist can go through an entire career without ever seeing a case of murder by poisoning. Give or take the odd polonium infusion by Russian agents, it is extremely rare. Not so in the 19th century, the golden age of poisoning, when the low cost and easy availability of lethal amounts of arsenic, strychnine and a variety of other drugs frequently made them the weapon of choice for the potential murderer. It was said in 1849 that ‘scarcely a week passes in which some instance is not brought before the public’.

Poisons were accessible for a few pence over the counter in any chemist’s shop, even to children, making it extremely tempting to bump off one’s parents, wife, husband, sons, daughters, friends, employers or servants should the mood and opportunity take you. Temptation was indeed rampant given the possibility of taking out an insurance policy against your victim’s future health from which you yourself would benefit if they died. You might also profit from a payout from a burial fund or loosely worded will. There was quite a good chance of getting away with it too, since the police were flat-footed and the first pathologists were struggling to catch up, only slowly developing foolproof tests for accurately detecting the cause of death.

Victorian murderers have provided a rich seam of material for historians in recent years – I have written a book on the subject myself – and The Secret Poisoner is the latest. Linda Stratmann has the benefit of having trained as a chemist. Her exhaustive survey traces many of the