THE death of a 53-year-old man, killed when his parked car was engulfed in a "fireball explosion", will remain a mystery, an inquest heard.

Simon Rowe died on September 2 in a layby on the A4129 Risborough Road between Longwick and Kingsey at about 1.45am.

At an inquest at Beaconsfield Coroner's Court today a witness statement from Amy Holland said she saw a "fireball explosion" in a layby as she was driving home.

She said: "The flash was so bright it lit up the area around it."

Ms Holland said she saw two other cars parked in the layby as she drove past.

Pathologist Rick Pangarhi said Mr Rowe died from severe burn injuries.

But he also discovered two heart conditions which meant he could have "dropped dead" at any moment, although his family said Mr Rowe was unaware of this.

His wife, Jane Rowe, said that evening she had a ‘bit of a disagreement’ with Mr Rowe after friends left. But it wasn’t an argument and there was no shouting, she said. Coroner Richard Hulett said there was no need to go into further details about this.

She went for a bath and thought he was still at home.

She said she did not believe he killed himself and he was not depressed or worried about money.

Mrs Rowe said he would always carry a petrol can in his Range Rover.

Andy Gosling, from Bucks Fire and Rescue, said Mr Rowe was sat in the driver's seat, which was reclined, and the doors were closed.

He said the most intense part of the fire was in the passenger compartment which is probably where the fire started and believed it was probably a deliberate act.

Family asked if Mr Rowe could have leant back onto the petrol canister to make it crush and leak, but Mr Gosling said this is unlikely as the plastic canisters are meant to be crush proof.

Mrs Rowe said the electrics in the car were faulty as it kept locking and unlocking and asked if this could have caused a spark that may have ignited a petrol leak.

Mr Gosling said it was possible but unlikely as the spark would have to come through the protective covering of the doors.

DC Nick Hills said there was no evidence of third party involvement.

Police interviewed a man who the family suggested may have started the fire, but he was completely ruled out.

Coroner Richard Hulett said: "I have noted the general feel of all parts of the family as one of astonishment that he died in this way and complete disbelief that he might have done so in a deliberate, what we normally call suicidal way."

He said although Ms Holland honestly thought there were two extra cars in the layby she could have been mistaken after the shock.

He added if there were two cars in the layby at 1.30am they were "more than likely" engaged in some liaison and left suddenly when the explosion happened.

He said it would be wrong to record a verdict of suicide as he would have to be beyond reasonable doubt and whether it was a deliberate act would remain a mystery.

He recorded a narrative verdict which read: "At about 01:45 hours on 2 September 2012, Simon Rowe was in the driver seat of his Range Rover, stationary in a layby adjacent to the Thame Road near Kingsey when an extensive and rapid fire occurred causing his death."