Sir William of Tyburn was the original spirit of the River Tyburn and one of the sons of Father Thames. He is said to have died during the Great Stink in 1858 as a result of the pollution of the Victorian era. The river became inhabited by Lady Ty, a new genius loci of Mother Thames’s court in the 1970s.
Peter have met this version of Tyburn twice, or so he thinks. The first time was when he was stuck under a platform at Oxford Circus Underground Station, and the second time when he was following Reynard Fossman through Green Park.
Tyburn may also have been responsible for the flood of water outside Lady Ty's house, when she almost was assassinated. If so, he was probably also seen by a David Hantsworth.