A biker accused of dangerous driving at 150mph on the A38 is to face a retrial after a jury failed to reach a verdict.

High Court judge, the Hon Mr Justice Field, offered to accept a 10-2 majority verdict when it became clear that the eight-man, four-woman jury at Plymouth Crown Court could not agree unanimously.

But after more than five hours of deliberations, the foreman told the judge there was no likelihood of their reaching a verdict.

The judge said the case against Oliver Marriott was a relatively straightforward one, but added that the jury had conscientiously tried to get to grips with it. He then discharged the jury and ordered a retrial after prosecutor David Gittins asked for one.

Mr Gittins had claimed Marriott, 21, put lives at risk when he was caught on camera "racing" out of Plymouth at 150mph. Marriott, who denied a single charge of dangerous driving, claimed the speed gun reading was inaccurate and he reached just 90mph when he sped up the A38 towards Plympton on December 20, 2008.

Marriott, from Pillaton, near Saltash, was on his way to meet a friend when he rode his Kawasaki ZX636 past a police van carrying out speed enforcement. PC David Williams told the court he was parked in a layby on the westbound A38 between Marsh Mills and Plympton when he heard the high-performance, six-speed bike approaching on the other carriageway.

He told the court it was the fastest vehicle he had ever recorded and at that time he thought Marriott was going to collide with the rear of the vehicle in front. Mr Gittins told the court Marriott was "racing into the distance", crouched low over the bike's petrol tank to maximise his speed, when he was forced to brake.

He described the green Kawasaki, which can reach speeds of up to 162mph, as a powerful machine.

He added: "He was not only putting other people's lives at risk but putting his own life at risk as well.

"It could have been a disaster for anyone else on the road."

Marriott initially denied riding the bike when police went to his house on Christmas Eve, but admitted it was him when shown stills from the video, the trial was told.

He also accepted holding only a licence for motorcycles with up to 25kw of power – well under the 87kw of his Kawasaki.

Speed gun specialist Stephen Langdon insisted the readings were accurate, describing how the Home Office-approved Lastec LTI 20-20 device threw out 43 invisible infra-red laser beams within a third of a second.

They each bounced back showing the object's speed and distance.

However, defence witness David Burgess, a consultant forensic collision investigator, told the jury: "There is scope for error with this device."

He said the laser beam could have fallen on nearby vehicles, giving a warped reading – and estimated Marriott's braking time was consistent with a speed of about 89mph.

Marriott was released by the court but will face a retrial before a fresh jury on a date to be fixed.

Oliver Marriot denied a single charge of dangerous driving.