A district judge hearing the case of a policeman accused of travelling at speeds of up to 159mph said that the officer's employer was also on trial.

District Judge Bruce Morgan, sitting at Ludlow Magistrates' Court in Shropshire, made his comments after hearing conflicting evidence about good practice when it came to testing patrol cars at West Mercia Police.

He called for the head of the force's traffic department to come to court and make the position clear. It was not fair, he said, for this burden to have fallen on the shoulders of sergeants and inspectors.

Mr Morgan is trying the case of Pc Mark Milton (38), who was recorded travelling at 159mph on the M54, at 84mph in a 30mph zone and 131mph near his Telford base.

Milton, who is a Grade I advanced driver, has told the court he had taken the 3.2-litre GSI Vauxhall Vectra out to assess its capabilities.

The officer, from Bratton, Telford, who denies a charge of dangerous driving and five separate speeding charges, was recorded travelling at speed on the car's camera.

Speaking on the third day of the trial, the judge said he had heard evidence from one officer who would never advocate testing cars in built-up areas and would stick to 30mph and 40mph speed restrictions.

David Twigg, defending Milton, said there was no evidence of a written policy governing what advanced drivers could or could not do on the roads.

The trial was adjourned until May 18.