A passer-by who witnessed a carjacking told a jury at Oxford Crown Court he was 100 per cent sure the man who carried out the attack was Anthony Joyce.

Joyce, 20, of Old Abingdon Road, in Oxford, denies robbing Stuart Johnson at knifepoint in January last year.

Mr Johnson was driving north along the A4010 near Princes Risborough, in Buckinghamshire, when he stopped by the side of the road because his black Honda Civic had been shunted by a white Ford Transit van. The court heard one of the three occupants, believed to be Joyce, then stole the car at knifepoint.

Eyewitness Thomas Baxter saw two men talking to Mr Johnson at the side of the road as he drove past the scene of the robbery. He said: "There were raised voices. There was some sort of discussion or argument."

Mr Baxter, who later picked out Joyce in a police identity parade, said there was no question he was the man who stole the Honda.

He said: "The incident lasted 10 to 15 seconds, but I know what I saw."

Ben Narain, defending, told the jury Mr Baxter had not got a continuous look at his client and that because events had unfolded so quickly, Mr Baxter was mistaken.

He also pointed out it had been getting dark at the time, at 4.45pm.

The trial is expected to finish on Wednesday.