Robert Wilson, 59, of Long Lane, Cookham, sadly died after the articulated lorry he was driving crashed through the central reservation and drifted over to the other side of the motorway earlier this year.

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His lorry crashed into another lorry, driven by Gary Prince, on the M40 northbound between junction 3 and junction 4 just before 6.30am on Monday, June 22.

Police statements by several eyewitnesses read out at Beaconsfield Coroner’s Court revealed Mr Wilson’s lorry was travelling on the M40 southbound when it “drifted” over to the central reservation.

The eyewitnesses described seeing Mr Wilson’s lorry crash through the barrier and into Mr Prince’s lorry on the northbound side.

John Appleton, who was on his way home from work, said: “A large heavy goods vehicle…came straight through the central reservation barrier towards me.

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“It was like a rocket. It impacted with the tipper lorry in what looked like a head-on collision.

“The lorry came through the barrier like it wasn’t there. It happened so quickly.”

Ian Bridge, who was also driving on the M40 that morning but on the southbound carriageway behind Mr Wilson’s lorry, said he was about to overtake the lorry to come off at the Beaconsfield exit (J2) when he saw it move into the middle lane.

He said: “It didn’t have its indicator light on.

“I stayed away from the lorry and watched it continue into the fast lane and hit the central barrier, [going] onto the other side of the motorway.

“It then carried on into the slow lane and struck the driver’s side of the trailer on the lorry going northbound.”

And Gary Prince, whose lorry Mr Wilson’s crashed with, said when he noticed it coming towards him, it was “less than a lorry length away”.

He added: “I could see it coming at me. The lorry had cleared the central reservation.

“I must have turned slightly left as it hit me from behind me. I was pushed back by the impact.”

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Thames Valley Police collision investigator James Henderson said Mr Wilson was wearing his seatbelt but there was no evidence of him having braked or swerved to avoid the crash barrier, and there was nothing wrong with his vehicle that could have contributed to the crash.

Road conditions were also clear and visibility was good, he added, with various video footage corroborating the eyewitness accounts.

Mr Wilson’s distraught wife, Eunice, questioned why they were not able to check if Mr Wilson had a medical episode, such as a heart attack, before the crash.

Senior coroner for Buckinghamshire Crispin Butler said there were "limits to what the pathologist could undertake" in the postmortem given how serious Mr Wilson’s injuries were.

He said several of Mr Wilson’s organs were not able to be identified, adding: “The severity of the injuries that he sustained have compromised dramatically the ability to identify a medical event beforehand.

“His injuries were incompatible with life. We can’t identify anything prior to the injuries.”

Mr Butler also said Mr Wilson had to be identified using DNA from another relative.

Breaking down in court, Mrs Wilson said: “How can I live with not knowing what happened to him [beforehand]?

“It’s an absolute nightmare, I don’t know how I’m going to live with that.”

Mr Butler said: “There is a possibility of a medical event occurring just before this deviation, but it cannot be identified from the pathologist’s point of view.

“His injuries were catastrophic.”

The medical cause of death was said to be multiple injuries and Mr Butler recorded a conclusion of a road traffic collision.