A ST John Ambulance volunteer has told a jury how a drunken man held a knife at his throat and demanded money.

Daniel Horton was walking home after being on duty at the Riverside Festival in Pershore last summer.

But he was allegedly confronted by 20-year-old James Yarwood who blocked his path, Worcester Crown Court heard.

Mr Horton, 18, described how he was asked for £3, gripped in a headlock and threatened he would be knifed.

He was dragged into a dark alleyway - but shouted for help as a couple walked by and his attacker fled empty-handed.

He picked out Yarwood, of Avon Bank, Pershore, on a police identity parade, and said he had seen him before outside a youth club and in a supermarket in the town.

Yardwood denies attempted robbery on July 23 last year.

Mr Horton was in uniform and carrying his medical bag and a rucksack when he was stopped in Head Street, Pershore, at 10.40pm by a youth who staggered and smelled of alcohol.

"He pushed me up against a wall and brought out a red-handled knife. He held it against my throat and said he would use it," he told the jury.

When the robber demanded to look in his bag, Mr Horton told him a bleeper would go off inside it, in an effort to deter him.

He was dragged into an alley but then heard the voices of a couple.

"I yelled to them to help me. They helped me home," he said. "I was very upset, tearful, very frightened. I was also angry."

Mr Horton, a supermarket worker and youth leader, said he was face-to-face with the defendant for most of the 10-minute incident and recognised him as someone he had seen several times before.

Nicholas Webb, prosecuting, said the couple later came across Yarwood loitering in Head Street. They asked him his identity and he gave the nickname "Yardie".

He told police he had been drinking that night and his memory was blurred.

But Mr Webb said he later changed his story and admitted he may have bumped into the victim and asked him for money - but denied having a knife.

In an interview, Yarwood said there was a 70 per cent chance it was him who grabbed Mr Horton.

After being picked out at Worcester police station, Yardwood stated he did not believe he had carried out the offence.

The trial continues.