Mary Blandy was convicted of murdering her own father and was hanged for the crime. Mary was born in 1720 into a middle class family. Her father was a well-to-do lawyer and the town clerk of Henley on Thames, in Oxfordshire. Mary was, by all accounts, an intelligent woman and she was well educated.
Keen to see his daughter marry well, Francis offered a dowry of £10,000 (a huge sum of money at that time). However Blandy’s entire estate was only worth about £4,000 and he could not have honoured the bargain. Still, the offer attracted a man named Captain William Cranstoun in 1746. Cranstoun was the son of a Scottish nobleman. In 1747 he asked to marry Mary. Francis agreed and even invited him to move into the Blandy home.
However Cranstoun was already married. When Francis Blandy found out, naturally he was enraged. However Cranstoun managed to persuade Mary and her mother that his marriage was invalid and would soon be annulled by the Scottish courts. Cranstoun moved to London to await the court’s decision. Unfortunately the Scottish court ruled that his marriage was legal.
Cranstoun persuaded Mary that he had a ‘love powder’ that if she mixed it with her father’s food and drink, it would change his attitude. He would start to like Cranstoun. The ‘love powder’ was actually arsenic. It’s not clear if Mary naively believed Cranstoun of if she realised what the powder actually was. In any case, her father fell ill and gradually worsened. He died on 14 August 1751.
Nevertheless, Mary was not arrested until the following year, 1752. Cranstoun heard of the arrest and fled abroad to France. Mary was hanged on 6 April 1752.