Calvin Smith, aged 19, pointed the imitation pistol at former Royal Marine Alan Patterson in front of terrified Metro passengers, Newcastle Crown Court was told.

Smith and two other youths had already assaulted a passenger in an unprovoked attack just moments earlier at Whitley Bay Metro Station.

And when Mr Patterson, aged 41, got out of his cab to help, Smith pulled out the realistic-looking black handgun from his jacket and threatened to kill him.

He then fled after the incident on February 26 of this year.

He was arrested five days later, but only told police where he had stashed the gun – under a bin at his parents' home – when he realised he was unlikely to be granted bail.

Smith, formerly of Argyle Street, Tynemouth, admitted possessing an imitation firearm with intent to cause fear of violence and assault by beating when he appeared at Newcastle Crown Court.

Mr Recorder Jeremy Richardson jailed Smith for three years.

He said: "This was an extremely serious incident in a public place where a public service worker and innocent members of the public were terrified and feared for their lives.

"The citizens of this region who use the Tyne and Wear Metro system and other public transport, together with the staff, have a right to be protected from mindless hooligans who plague the streets with violence and thuggery.

"The courts must play their part in making it plain severe sentences will be passed on those who resort to threatening and attacking passengers and staff on the public transport system."

Mr Kingsley Hyland, prosecuting, said Mr Patterson believed the gun was real.

"He is a former Royal Marine and later said he believed the firearm to be genuine," said Mr Hyland.

"Fearing for his life he fled to the relative sanctuary of the driver's cab, where he locked the train doors to protect other passengers."

Mr Shaun Routledge, defending, said Smith had bought the gun off a friend, although the barrel was damaged and it could not have been fired.