An armed robber who unwittingly targeted an off-duty police officer and then bit and headbutted a second officer during his arrest has been sentenced to 18 months in a young offenders institution.

Billy Draper, 18, formerly of Oak Trees, Maidstone, was sentenced at Maidstone Crown Court on July 3, having previously pleaded guilty to robbery, and assaulting a police officer.

Draper had approached the off-duty officer, who was from another force, in Maidstone town centre on March 1 as he was walking with his girlfriend and another woman.

He verbally abused the victim before pulling a knife from a jacket pocket and demanded ‘everything’, despite the fact the officer had identified himself.

The victim passed Draper items including cash, two mobile phones and his warrant card.

Upon opening the warrant card Draper retreated to a nearby pub, whilst the victim followed him and called for police backup.

Draper was then pointed out to Kent police officers, but as he was being arrested he headbutted and bit a police constable.

When interviewed Draper said that he had been out drinking but claimed he had no memory of either the robbery, or assault.

Detective Inspector Karen Festing, said: "It is likely that Draper had set out to rob the first people that came in his direction, but he clearly had no idea that the victim he chose was a serving police officer.

"It was only when Draper properly looked at the warrant card that the penny dropped, but by this time we had already been alerted to his behaviour and the victim had followed him and identified him to local officers.

"I’m pleased with the sentence as there is simply no excuse to be carrying a weapon, or for these type of actions on our streets."