Amen Court

A black shape, said by some to be a dog, is said to "slither" across the top of the wall, sometimes accompanied by a "vile smell", the sound of boots scuffing and chains rattling. Some suggest that the shape harkens back to the cruelty of Newgate prison's gaolers (the prison used to stand close by) while others say that it is Jack Sheppard who ingeniously escaped in 1724. Yet others say that the shape is that of 13th century sorceror, whose body was eaten out of desperation by fellow inmates of Newgate. Yet others say that the "shape" is actually a black dog, and it is the manifestation of a former prisoner named Schoiler, who was eaten by fellow starving inmantes.

Link: Londonist

Link: Shady Old Lady