A police constable accused of travelling at speeds of up to 159mph while on duty in a force car has insisted he had only been trying to "familiarise" himself with the new vehicle.

Mark Milton (38) is also alleged to have driven at 84mph in a 30mph zone and 131mph on an A road in and around Telford, Shropshire, where he was based as an officer for West Mercia Police.

Giving evidence to magistrates in Ludlow, Shropshire, the Pc, who qualified as a Grade I advanced driver in 1995, said he had taken out the newly- commissioned, unmarked 3.2 litre GSI Vauxhall Vectra to assess its capabilities.

He told the court he had never driven the model before taking it out on patrol on the M54 and other roads in the early hours of December 5, 2003 but had to do so because the car he usually drove was at a workshop.

Milton, who denies a charge of dangerous driving and five speeding charges, gave a commentary as the court was shown video footage captured by the high-powered car's on-board camera.

He said: "I was having to learn straight away the characteristics of this new vehicle as I went.

" I had taken the opportunity to familiarise myself with that vehicle. It was part of a learning curve which involved getting used to how the steering worked, initially at low speeds, getting a feel for the braking system and getting used to the size of the vehicle."

Milton, from Bratton, Telford, said: "At no time did I consider that anybody would be at jeopardy given that even on advanced courses whilst still a student under instruction I was being encouraged to drive at speeds greater than 145mph on motorways," he told the hearing.

Milton said only officers attending refresher courses were being advised not to drive at speeds of more than 120mph on motorways or more than 20mph above the speed limits in restricted zones.

He said he would have observed recommendations had force policy been clearer.

The trial continues.