I think the police came to the conclusion he died as a result of a kinky game gone wrong. Apparently he would do this thing whereby he would almost pass out and die, but just stop that from happening in time.
That was the 'thrill'. But it went wrong.
Same with that actor David Caradine who died in similar circumstanes, except I think he hung himself up on a door and died.
But Gareth was also a cross dresser. Apparently police found £20,000 worth of women's clothes in his flat and a garage he had.