Much like the popular TV series X Files, Gary has been researching unexplained flying objects and extra terrestrial activity for most of his life.
While many people scoff at believers such as him, the former RAF and British Transport Policeman (BTP) believes he has evidence better than most.
While still a serving officer, Gary launched a national police database of UFO sightings and now has hundreds of records of bizarre incidents, including some that were witnessed by dozens of different policemen and women at the same time.
Now retired from the force, Gary, who lives in Holmfirth, has emerged as the UK's top 'ufologist'.
His expertise has become internationally renowned to the point where he recently gave evidence to a panel of top politicians in Washington DC.
He is now launching a new online magazine and has written a film script about Britain's most famous UFO case - the Rendlesham Forest incident.
It was during the nights of December 26 and 27 in 1980 that American servicemen stationed at RAF Woodbridge and Bentwaters in Suffolk reported mysterious lights in the nearby forest.
Gary said: "My interest began when I was 15 years old and I saw something with my girlfriend.
"There were bright lights with no distinct shape above us that seemed to spark a load of power failures in the area.
"But it was in the mid-90s when I got really interested when I came across a UFO magazine.
"I got all the books and I kept coming across reports from pilots who had seen things.
"I thought 'there's something wrong here' as the media are all saying we're lunatics but the pilots' accounts seemed plausible.
"Then in 1998 I had the idea for the police UFO database, which launched in 2002.
"Some of the stories that have come out are amazing. Of the 425 cases, 70% are multiple police witnesses.
"It's not just 3am sightings, getting it wrong because they're tired.
"In one case it's 24 officers across six counties at the same time."
Gary says he's had three sightings himself, including one above Holmfirth in August 2011.
For the sceptics out there Gary says: "What convinces me is not that one UFO searcher has got an alien body and he says 'told you so', or one's got a piece of a spaceship.
"As a detective for 24 years I've always looked at what would stand up in a court of law.
"Lots of people have been found guilty of murder without a body ever being found.
"I think the case for genuine extra terrestrial is overwhelming if you look at all the evidence.
"Yes 97% of cases can be explained but 3% defy all explanation."
Gary said many incidents featured physical evidence such as depressions in the ground, high levels of radiation or the soil around a UFO sighting changing its properties and becoming waterproof.
And he said many UFO's could not be attributed to 'stealth' military aircraft as their movements were not physically possible and they were usually silent.
He said: "We're dealing with something that's real, it's not just lights in the sky."
Gary plans to publish a book UFOs - Through Police Eyes and his online magazine, www.ufotruthmagazine.com, launches on June 25.
