A schizophrenic man took a driving instructor's car at knifepoint as a learner was doing a three-point turn because he heard voices in his head, a court heard.

Armed with a large kitchen knife, Richard Wakefield, 21, opened a door of the car as the manoeuvre was being carried out in Campbell Road, east Oxford.

He held the blade towards the woman behind the wheel and told the instructor he would use it if he had to, Oxford Crown Court heard yesterday.

Peter Ross, prosecuting, said: "He told them to start walking towards Florence Park. He got in and drove off towards Cowley Centre."

Two motorists who saw the incident followed him on to the southbound A34. One gave a running commentary to police on a mobile phone.

At the Abingdon North junction he changed to the northbound carriageway and drove as far as the Botley interchange, where he was stopped by a waiting police patrol car.

Doctors said that Wakefield, of Wilsdon Way, Kidlington, was not mentally fit to be detained after the incident, which happened at about 4pm on September 12 last year. He was treated for six weeks at the Littlemore Hospital, Oxford, before being questioned by police in December.

Mr Ross said Wakefield's father told police his son had recently accompanied him on a car journey to Cardiff and later heard voices telling him he had to steal a car and return. His son was trying to drive to Cardiff but got lost.

The court heard that Wakefield, who admitted robbery, was a university student who studied from home due to schizophrenia, from which he had suffered since 2000.

When the victims were told about his illness, they said they did not want him prosecuted, Mr Ross added.

Miss Zoma Angelidez, defending, said it was a tragic case for all concerned.

Judge Tom Corrie said robbery using a weapon could attract a prison sentence of five years, but this was an exceptional case and Wakefield had "become a tragedy for the whole family".

He imposed a two-year community rehabilitation order with a condition that he should comply with psychiatric treatment.