50 Berkeley Square is a reportedly haunted townhouse on Berkeley Square in Mayfair, Central London. In the late 19th century it became known as one of the most haunted houses in London,[1] with its attic room said to be haunted by the spirit of a young woman who had committed suicide there.
Researchers have since suggested that the stories may have derived from the odd behaviour of house's occupant, Thomas Myers, who slept during the day and made unusual sounds in the house at night.[2][3] It has also been noted that many of the stories about the house were exaggerated or invented by later writers about its ghosts.
Taken from Wikipedia at:
https://en.m.wikipedia.org/wiki/50_Berkeley_Square