A Saga sales agent died at the company's Christmas party from "a perfect storm" of factors that caused heart failure, a jury has heard.

David Ivin – who was nearly 16 stone – had been drinking at the 2012 bash when he was confronted by security men.

During the argument, the 36-year-old was forced to the ground by two bouncers at the Leas Cliff Hall in Folkestone.

Now a Home Office forensic pathologist has told the trial of men accused of his manslaughter that one of the factors that had brought about the cardiac arrest was caused by compression to his neck.

Dr Ashley Fegan-Earl said some of the internal injuries to Mr Ivin's throat were caused by an arm lock with pressure being exerted "a minimum of between 20 to 30 seconds".

Brent Wright, 36, of Broomfield Road, Folkestone, and Martin Barnwell, 30, of St John's Road, Elvington, Dover have both denied manslaughter.

Prosecutor Duncan Atkinson told the jury at Canterbury Crown Court: "We say the restraint of Mr Ivin was unnecessary and the manner and duration was excessive and contrary to proper training and techniques.

"It posed an obvious and serious risk to Mr Ivin's health."

Mr Ivin had been working on the company's home care-personal assistance team and had been invited to one of two Christmas bashes on December 13.

The door supervisors worked for 219 Security, which had been recruited to provide security at the event.

The prosecutor said Mr Ivins had attended the invitation-only event after drinking in the nearby Scuba Bar at the Portland Hotel.

"This was a Christmas party and Mr Ivin's blood concentration showed he had a high degree of intoxication."

But the pathologist said other factors played a part in the unnatural death – other than sustained pressure on Mr Ivin's throat that had fractured a tiny bone.

That had also caused bruising to nerves that control heart beats and pressure can make the heart slow down considerably.

Dr Fegan-Earl said an examination of Mr Ivin's liver showed evidence of him being a heavy drinker.

And being obese – Mr Ivin was 5ft 11in with a body mass index of 30 – would have caused him problems breathing after being held face down.

The expert said someone struggling would exhaust oxygen in their muscles causing lactic acid to be formed which, in high concentrations, would also interfere with the heart working properly.

"It is almost certain that Mr Ivin would also have been producing adrenalin, the hormone produced when you are nervous or under stress and can make the heart more irritable and the development of an abnormal rhythm," he said.

"Deaths caused during the procedures of restraint are undoubtedly highly complex and in my experience involve a large number of different factors.

"Such factors will combine together and create a perfect storm in which the heart and lungs cease to function."

The argument between Mr Ivin and the security guards happened when Mr Ivin attempted to return inside the hall using his SAGA ID card rather than the party invitation.

The two bouncers took hold of Mr Ivin's arms and "forcibly moved" him to the front doors of the hall, it was claimed.

The prosecution has claimed witnesses who saw the angry confrontation reported the bouncers ended up on top of Mr Ivin.

The trial continues.