In the summer of 1701, a 36-year-old English widow, Mary Grosvenor, arrived in Paris on her way home from a visit to Rome. She had converted to Catholicism some eighteen years earlier and included in her small entourage was her confessor, a Benedictine monk named Lodowick Fenwick.

Mary was in fragile mental and physical health. She had been forced to leave Rome early because she had felt unwell, and she had been so ill on the journey back that the party had stopped in Lyons for three or four weeks while she was bled and dosed with medicines. Her behaviour was erratic; she suffered from fits, spoke wildly and on one occasion had to be forcibly restrained. ‘She fancied she could fly, and thought she could throw herself out of the window and do no hurt,’ one contemporary observed. Fenwick, who began to behave more like a carer than a confessor, ordered the windows of their hotel nailed shut after that episode. He also began to police her social life, decreeing who could and could not visit her.

Once settled at the Hotel Castile in Paris, Mary continued to behave oddly. Fenwick took to slipping laudanum into her food after she refused to take any more medication. He also continued to turn away visitors. One person who was allowed to call, however, was his brother Edward, a hard-up