The face of Caroline Ansell, an inmate of Watford mental asylum, lit up with glee. Another cake had arrived from her sister Mary – the second this month. She shared the treat round the ward, and promptly half a dozen inmates became violently ill. Caroline herself was among them, and she died five days later.

A post-mortem discovered that the cake Mary had sent was laced with poisonous phosphorous. It seemed that Mary, a 22-year-old servant, had wanted to kill her mentally ill sister for the life insurance money – £11. 5s.

Curiously, the jury at Hereford Assizes was not told that Mary was also probably insane. She had two sisters in mental homes and all her aunts had died in asylums. The jury foremen said none of the jurors believed she would be executed, and the prison chaplain described her as “simple.”

For all that, Mary was bought to the scaffold on Wednesday, July 19th, 1899, at St. Albans Prison.