Jamie Burnell, lead investigator for Watford Paranormal group, was one of nine people ghost-hunting in the park between 9.30pm and 3am on Saturday night.
The 33-year-old said the park is haunted by the ghost of Lord Arthur Capel, who was a Royalist during the Civil War and met his end when he was beheaded in 1649.
Paranormal groups meet every year around March 9 trying to spot the headless spirit of Lord Capel, as that is the anniversary of the sightings.
Speaking about the photo, Mr Burnell said: "The more I look at it the more I believe the spirit entities were trying to show themselves.
"There are faces on their sides and I can see almost a full body apparition. The more I look at it the more I see into it."
Mr Burnell said that a member of his group, Alexander Ray, had to keep holding his breath when he took photos because they did not want to compromise the picture at all.
Read Full Story: Watford Observer UK