Nearly 75 years ago, what is still considered one of the best ghost photographs of all time was taken at Raynham Hall, Norfolk. Ever since, it has been held up as convincing evidence for the existence of spectral forms but, as Alan Murdie discovered, long-forgotten files on the case point to a different conclusion.

The photograph known as 'The Brown Lady of Raynham Hall' is probably the most famous picture of a ghost ever taken. Captured on 19 September 1936 by two photographers, the picture s...