A combination of still photographs taken from video shows a man trying to lock himself in a holdall

Investigation … a man tries to lock himself in a hold-all.

GARETH WILLIAMS, the MI6 spy, was ''dead or unconscious'' when placed in a sports bag because ''not even Houdini'' could have locked himself in it, an inquest has heard.

Peter Faulding, a former Parachute Regiment reservist and expert in confined rescues, said he was convinced another person was involved in putting Mr Williams into a holdall and padlocking it.

He said the idea of him doing it himself fell into the category of ''unbelievable scenarios'' and that even the world's greatest escapologist would have struggled.

His revelations will intensify theories that the 31-year-old code-breaker may have been killed and dumped in a bag in the bath.

The inquest at Westminster Coroner's Court is investigating the death of Mr Williams, whose decomposing, naked body was found in the holdall in the bath at his London flat in August 2010.

It also emerged at the inquest that a home-made video showing Mr Williams naked except for black leather boots in which he ''wiggles and gyrates'' with his back to the camera was on one of his iPhones.

Evidence of visits to bondage and fetish websites were also found on his phones and laptops.

The inquest heard that his last internet activity was during the early hours of Monday August 16, a week before his body was discovered, and one of his phones had had its factory settings restored - the equivalent of wiping a computer hard drive.

The issue of whether Mr Williams could have locked himself in the bag is central to the inquiry and has led to theories that a second party was involved.

In the fifth and most dramatic day of the hearing, video footage of attempts to recreate climbing into an 81-centimetre by 48-centimetre holdall and locking it was shown to the court. Mr Faulding, who is of similar height and build to Mr Williams, tried to climb into a bag inside a bath and lock it himself, failing 300 times.

He said: ''My conclusion is that he was either placed in the bag unconscious or he was dead before he was put in the bag.''

When asked if it was impossible for Mr Williams to have locked himself inside the bag unaided Mr Faulding said: ''I can't say it was impossible but I think even Houdini would struggle with that one. My personal belief is that it could not be done.''

Mr Faulding suggested Mr Williams was then put in the bath ''to reduce body fluid or decomposition''. He said it would have been ''very, very easy'' for a single person to lift Mr Williams into the bath and there would have been marks in or around the bath if he had done it himself.

Telegraph, London