The ghostly image of a young boy's face appears above a vapour trail in the vaults of the Whittington Hospital. Picture: Polly Hancock

A bolt of light flashes across a corridor, and the illuminated face of a young boy appears out of the darkness.

Ghosthunter Leonard Low captured the spectre on film in 2007. Picture: Polly Hancock

This is the mysterious image which ghost hunter Leonard Low says proves that something paranormal lies beneath the Whittington Hospital in Highgate.

The father of two was visiting a friend who was having surgery in the Archway Road hospital when he was told by nurses of "a strange presence" in the 19th Century arches deep underground.

Armed with his camera and accompanied by a curious Whittington administrator, he descended down to the basement to investigate the paranormal tales.

"Nobody had been in this area for years," said the 44-year-old.

"The ground was crystallised like snow.

"We began walking down this long corridor with files all around us. We walked for around five or six paces when we saw something down the corridor moving.

"There was something hovering in front of us and getting closer and closer.

"We saw this trail of light it was flashing all over the place. Then I saw the ghostly image of the young boy."

Mr Low said he heard reports from nurses of a ghost like figure watching them, prompting him to investigate.

The Whittington hospital is steeped in history, dating back to the 15th Century when a leper colony was founded there.

Mr Low believes the ghostly apparition of a young boy who appeared before him was the spirit of a child called William who lost his life there in these early years.

It was not the first time the father-of-two has felt the presence of those beyond the grave.

When Mr Low was 21 an apparition of his sister in her nightgown appeared to him a fortnight after she died.

And dozens of people have reported glimpsing ghosts at his 18th Century Scottish tower, Tolbooth, which was used to imprison and torture women during the bloody witch hunts.

Describing the "extraordinary pain" he experiences when in the presence of a ghost, Mr Low said: "I get pins and needles in the back of my head and I find it hard to see.

"It is as if my skin knows there is something there."

The truth of the eerie apparitions within the basement of the Whittington is far from clear, but a spokeswoman for the hospital said they are aware of reports of a ghost lurking there.

The tale of the Whittington ghost is explored in Mr Lows new book, True Story of the Pittenweem Poltergeist.

A hospital spokeswoman said: "Whittington Health is aware that there have been ghost stories about sightings and feelings in the smallpox hospital over the years. There is no evidence but the tale continues."