A lorry driver who was using a hands-free phone may have been adjusting his seat belt when he lost control and overturned on a motorway, an inquest heard today.

Graham Elliott, 49, was heading back home to Calverley Crescent, Dagenham, at the end of his shift on May 11 when he crashed just before 5am.

The dad-of-two was chatting with a colleague shortly after leaving a service station when the lorry veered towards the hard shoulder, juddered violently as it hit the grass verge and then swerved sharply to the right, colliding with a crash barrier and overturning onto the M4 eastbound between junctions 11 and 12.

His body was found outside the cab of the lorry, having been thrown through the passenger window.

On long drives he would often speak to close friend Paul Surridge on the hands-free phone provided by Ford Motor Company, for which they worked.

His friend recalled at the inquest in Reading Coroner’s Court: “We spoke for three or four minutes when suddenly Graham let out a groan. I did not hear any smashing glass which might have made me think he was in a crash.

“I phoned Dagenham to say something was wrong and later got a call back saying Graham had overturned his lorry.”

A passing driver, Stephen Beresford-Wylie, recalled how he had to accelerate away from the lorry as it began to overturn.

He said: “I had left the first lane and it [the lorry] drifted half on the motorway, half on the hard shoulder. It then swerved towards the car – the lorry was fully out of control. I accelerated and swerved to the right to avoid it. It was going to hit the barrier but instead it overturned.”

An inspection of the vehicle after the crash revealed it was in working order with no mechanical faults and there were no faults with the road surface.

A collision investigator for Thames Valley Police, Stephen Moffatt, said: “There is evidence that the use of hands-free phones is very distracting and not as safe as we think they are.

“I have a theory which I can’t prove, which is that he was fiddling around with his seatbelt. Mr Elliott’s friend called him on his hands-free phone.

“The prolonged loss of attention [was] possibly exacerbated by mobile phone use.”

A pathologist who examined Mr Elliott’s body found that the cause of death was crushing of the chest, which triggered a lung haemorrhage and internal bleeding.

Assistant coroner for Berkshire, Emma Jones said: “I find a temporary loss of concentration caused Mr Elliott to lose control of the vehicle and he was unable to correct the situation.”

A conclusion of unnatural death by road traffic collision was recorded.