This sinister snap is believed by some to show the ghost of a night watchman, still faithfully standing guard at a country house, hundreds of years after he died.
The apparition was snapped in an allegedly haunted 650-year-old building that is being investigated by by paranormal sleuths.
They believe it is the Night Watchman, a spirit from the 17th century, still guarding the Rye House Gatehouse in Hertfordshire.
Micky Gocool, lead investigator of North London Paranormal Investigators, said: "We're not in the business of just trying to spook people.
"We always look for the rational and logical explanations, so we deliberately conducted our investigations at Rye House Gatehouse during the daytime.
"I've been conducting paranormal investigations for 25 years now and I'm confident in saying that this is a site with activity."
The park's senior ranger Gareth Winn said: "It was taken by a member of the public as part of a paranormal investigation.
"I was there at the time. It was interesting because the room where it was taken was where we get a lot of activity.
"It affected two of the mediums who were there and they ran out of the room to vomit.
"When it happened the temperature dropped and we got an electric surge. You get a lot of static and that is an indication that something is about to happen.
"The equipment that they brought picked up on electromagnetic energy the spirits give out.
"The instrument all went haywire and then people ran out being sick.
"We were in the same room in August last year and a member of the public in another investigation passed out in front of me.
"It is in the same room. The evidence suggests that the room is the centre of activity."
Winn says he knows the name of the armed watchman and why his soul may be haunting the site, but does not wish to disclose details for fear of attracting hoaxers.
He said: "He was the armed guard for the manor house. When the gentry slept he stood guard.
"It was a dangerous time to live and he was there to protect the house.
"He used to carry a lantern and walk along the building's wall.
"It is thought the lights that people have seen in the building's roof in the past have been him."
Rye House Gatehouse is open on Sundays until September 25 between 11am and 4pm