A street confrontation in which a young St Albans man was stabbed to death began with the kicking of a car, a court was told on Monday.

Emille Stapleton, 20, known as "Milz" was fatally wounded by a knife plunged into his back in the early hours of October 24 last year in London Road.

The incident with the car, in which Mr Stapleton was a passenger, happened about three hours earlier, a jury heard at Cambridge Crown Court.

As the group of friends were driving back along London Road at about 3am, Mr Stapleton saw one of the same group from before and got out. But the court was told that a crowd then "appeared out of nowhere".

It is alleged that defendant Paul Crosbie, 26, of no fixed address, was alerted to what was happening and armed himself with a kitchen knife before he left a flat in nearby Benedictine Place.

It's claimed that Crosbie, also known as "Irish", arrived on the scene and stabbed Mr Stapleton, a former pupil of Marlborough Science Academy, with such "severe" force that he died from internal injuries before help arrived.

Crosbie pleads not guilty to murder and claims he acted in self-defence.

Opening the case to the jury of six men and six women, prosecutor John Farmer said the only explanation Crosbie had given was in a phone call to a police operator two days after he was arrested and bailed.

He claimed he was responsible for the stabbing and said the knife could be found under lead flashing outside a bedroom window of the Benedictine Place flat.

In the call, played to the jury, Crosbie said: "I didn't mean to do it.

"Obviously I am going to jail for a long, long time."

Outlining what happened that night, prosecutor Mr Farmer said a man called Ashley Jones was driving a VW Polo accompanied by Mr Stapleton and Islam Whetter and girls Bethan Lambert and Dominique Irons.

At about 11.30pm a group of young men and women, including Crosbie, were crossing London Road and obstructing traffic.

"Mr Jones had to slow down. He claims the car was kicked," said Mr Farmer.

He said the three men in the car got out and a confrontation between the strangers took place.

Mr Stapleton had taken cannabis but no alcohol, Mr Farmer added.

Mr Jones was then said to have driven off, leaving the other angry group behind.

However, he said that three hours later Mr Jones was driving back down London Road when Mr Stapleton told him to stop.

Mr Jones saw one of the earlier men was there.

Mr Stapleton got out, as did Mr Whetter. The other three stayed in the car.

"That man was not alone. A crowd emerged. The extraordinary thing is that one way or another the core of the group was still there.

"Crosbie was nearby, in a flat. He was alerted to events which were unfolding on the street below.

"He equipped himself with a kitchen knife and left to join in the affray. He was not connected with or involved in the incident at all, not threatened by it, it's nothing to do with him other than his mates are involved," alleged the prosecutor.

He said no witnesses actually saw the stabbing.

Crosbie said nothing in interview after he was arrested and was released on bail the next day.

On October 27 he rang police and admitted he was responsible for the stabbing.

He said he would hand himself in when he had said goodbye to his son and his mother and sorted out a few things.

Crosbie was spotted and arrested near the Galleria, Hatfield, a few days later.

The trial, which is due to last two weeks, continues.