It is after dark and, ordinarily at such an hour in April, office buildings are unoccupied.

The people should have gone home and the only sign of life ought to be the bleeping green light of a dormant photocopier.

Tonight, it would seem though, is no ordinary night.

Take a look inside one building in Wallington and you will see figures moving.

Take a closer look inside and you will see each one of those figures is equipped with a camera.

Take a closer, and longer, look still and you will see a strange look in their eyes - a look which is perhaps part concentration and part fear.

They are members of Spiral, a new Sutton-based group who investigate the paranormal.

Armed with night vision video equipment, they carry out late night vigils of properties suspected of being haunted.

Claiming to be sceptics, they try to find logical explanations for any evidence of the supernatural they encounter.

Their ultimate aim however, is to capture on film clear, irrefutable - and spooky - footage of ghosts.

"We had our cameras on night-vision mode," Marq English says of their first vigil at a business premises last month.

"We turned the lights off at about 8.30pm and were there for four hours in the dark. We saw some flashing lights called orbs which people think are the first manifestation of the spirit.

"The chances of seeing a full manifestation is very, very rare. Although I'm an investigator, I've never actually seen a ghost.

"All it takes is that one bit of evidence though. Most people can get orbs now, but actually getting a manifestation on camera, that would be amazing, unbelievable."

In his role as a paranormal investigator, Marq has combined two of his long-term interests: all things supernatural and all things celluloid.

Although his day job is working on the stage door at New Wimbledon Theatre, the 40-year-old spends some of his spare time organising the Sutton Film Festival.

He also says he has been interested in what he calls "the big picture" all his life.

A natural melding of these enthusiasms, Spiral - who commit s what it observes to film - is different from other paranormal groups.

Rather than simply posting a written report on its website, Marq and co-founder of the group 25-year-old Alexis Pelling upload 20 minute films.

These mini-documentaries are the edited combination of night-vision footage shot by the group of about five carrying out the investigation.

As well as just shooting what they see, members also record electronic voice phenomena and conduct seances to try and interact with, as well as film, the dead.

"It's actually a lot of fun," Marq, of Endale Close, Carshalton, says. "People want to do something different as opposed to sitting in front of the TV every night.

"Your perceptions and everything change as soon as you go into night vision.

"I wouldn't say I was scared though. That time is yet to come.

"I'm thinking logically as well. If I see something or hear something, I'm thinking of a logical explanation before a paranormal one."

After its debut investigation at the office called the Studio House, Spiral are planning to stake out a 400-year-old Sutton church.

Future targets for their inquiring minds is the landmark old buildings in the borough - Carew Manor, in Beddington, and Whitehall, in Cheam.

"Proving the existence of ghosts would be the ultimate peace of mind - that there's another side, another aspect to our lives," Marq says.

"I've always been interested in seeing if there's anything beyond ordinary life. It would just show there's something more."

For more information about Spiral go to mevproductions.

co.uk/spiral.html. To suggest possible sites for investigation, email spiral@mevproductions.

co.uk.