This photo was taken at the National Maritime Museum, Greenwich, England back in the 1960's. It was taken by a retired clergyman Rev Ralph Hardy, who was visiting from British Columbia. He took the photo as he liked the spiral staircase. After his return back home, he got the photographs developed and one of his friends was looking through them and asked who was the figure on the staircase. Hardy was astonished to see the figure as he said no-one had been there at the time of taking the photo.
The photograph has been examined by photography experts and there is no evidence of tampering with the image. Speculation of who the ghost figure could be has given rise to the possibility that it could be the ghost of maid, who was said to have died on this very staircase around 300 years ago.
Personally, I like the way one of the arms looks longer than the other arm, almost as if it were made of particles and hadn't finished putting itself together to build a more solid image.