In life, she was a notorious society beauty. Dorothy Walpole, sister of Sir Robert, Britain's first Prime Minister, scandalised Georgian society by having an affair with a penniless lord before marrying an older widower - and dying, aged 40, in mysterious circumstances.
But her infamy spread around the world in 1936, more than 200 years after her death, when she was allegedly captured on film - in what many experts claim is the world's most compelling "ghost" photograph.
Over the years, this extraordinary image, called "the Brown Lady of Raynham Hall", has been the cornerstone of countless claims for the supernatural.
Now, 70 years after the picture was taken at Raynham Hall in Norfolk, a leading paranormal investigator has stumbled across evidence that it is a fake.
Alan Murdie - a barrister and also a researcher into the supernnatural - found the evidence in a dusty folder in the manuscripts department of Cambridge University library.
The file details an exhaustive investigation into the phenomenon shortly after the image was taken. Conducted by the Society for Psychical Research, it concludes that there is almost certainly a mundane explanation for the "spectral" image in the photo.
The evidence includes the discovery that the camera may have leaked light on to the photographic plate.
A descendant of Lady Walpole, the Hon Jonathan Walpole, said even if it wasn't his ancestor in the photo, she may well still be haunting the Hall. "The father of one of my friends swore that she walked past him on the stairs once."