A drug user who brandished a knife at a St John Ambulance volunteer in a bid to get cash faces custody.

James Yarwood targeted 18-year-old Daniel Horton as he walked home from being on duty at a Pershore festival last summer.

He demanded £3, grabbed the victim in a headlock and threatened to stab him, Worcester Crown Court heard.

Mr Horton, who is also a youth worker, escaped after John White and his girlfriend came on the scene in Head Street and helped him.

A jury took five hours to convict Yarwood, of Avon Bank, Pershore, of attempted robbery.

Granting the 20-year-old bail for a report, Recorder Patrick Thomas QC said he would be "astonished" if he was sentenced to anything other than custody.

He praised Mr White for being "a decent citizen who acted extremely well". He had shown kindness and courtesy to the victim.

Last year Yarwood was given probation for possession of heroin and cannabis. He also had another drug conviction and one for being drunk and disorderly.

The recorder imposed a nightly curfew on the defendant to stop him getting drunk.

The court heard how Yarwood blocked Mr Horton's path on July 23, then dragged him into a dark area and held a blade at his throat.

"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.

After he was dragged into the alley, he 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."

After Mr Horton yelled to Mr White for help, Yarwood ran off empty-handed.

Mr White took the terrified victim to his home and then scoured the streets for his attacker. He found Yarwood loitering near the scene and demanded his identity. He gave the nickname "Yardie".

Mr Horton had seen Yarwood in the town on previous occasions outside a youth club and in a supermarket. He was able to pick him out on a police identity parade.

Yarwood claimed he was too drunk to remember anything. Then he said he was 70 per cent sure he had gripped the victim. But he denied producing a knife.