An elderly motorist killed himself and a 19-year-old after driving down a motorway fast lane in the wrong direction, an inquest has heard.

Witnesses said retired jockey Tony Riddle, 69, from Cardiff, south Wales, appeared to be on "a suicide mission" after leaving from a service station on the westbound M4 and driving for four miles into oncoming traffic.

It seemed surreal - it took me a few moments to realise what was really happening

Detective Chief Inspector Norman McKeaveney

A driver on the eastbound carriageway drove alongside Mr Riddle's car, desperately trying to attract his attention by leaning out of his windows and waving his arms.

But that failed to stop the ailing pensioner before he smashed headlong into the car driven by student Jonathan Selwyn, also from south Wales, in a 140mph-impact crash which killed them both in a fireball.

The inquest at Swindon heard details of the incident on 27 March, described by one witness as "surreal".

Onlookers stared in disbelief as Mr Riddle turned the wrong way on to the exit slip road at Membury services.

Jonathan Selwyn ha no chance to avoid the car

Retired traffic policeman, John Collis, was among hundreds of people who dialled 999 as the pensioner sped off on his final journey.

"I saw a Nissan Micra exiting the services the wrong way. My first thought was that it would try to do a sharp left turn but as it happened the Micra just carried on.

"I could see an elderly gentleman driving and he looked pale and ashened.

"He seemed calm and totally oblivious to the error he had made."

Detective Chief Inspector Norman McKeaveney of Wiltshire Police was travelling on the westbound M4.

'Surreal'

"I could see a small blue car in the outside lane, on the other side of the barrier - but travelling in the same direction as me.

"It must have been doing 70 miles per hour. It seemed surreal. It took me a few moments to realise what was really happening.

"I saw six or more vehicles swerve violently to try to avoid this car.

"I saw a male driver with his head and arms out of the window trying to draw the attention of the driver.

He was also trying to warn traffic to move across."

Moment later there an explosion and a ball of flames as Mr Riddle's car ploughed head-on into the Vauxhall Calibra being driven by Mr Selwyn.

Depressed

Mr Riddle's niece, Linda Harris, told coroner David Masters her uncle told her he was planning to drive to Marlborough area where he had been a stable lad and jockey many years before.

She also said he had been depressed by the death of his wife the previous year.

Mr Selwyn, from Aberdare, was an aeronautical and mechanical engineering student at Bristol University.

Both men died from multiple injuries.

A police investigation found signage at the services was inadequate, despite no-entry signs being posted where Mr Riddle had driven onto the motorway.

Since the crash, new signs have been put up and a review of all UK service stations is in progress.

Mr Masters said he had considered a verdict of unlawful killing on Mr Selwyn, but he could not be certain how the pensioner was in those last miles along the M4

He recorded an open verdict on Mr Selwyn and a verdict of misadventure on Mr Riddle.