A pensioner and serial offender who sexually assaulted a 14-year-old boy on a bus will serve an 18-month jail sentence.

Edward Prior, 78, of Fulwell Road, Teddington, sat next to the victim on a 33 bus on May 31 this year, and attempted to strike up a conversation before producing a photograph of a naked woman from his pocket.

The convicted paedophile, who was a law-abiding citizen until the age of 72, then held the picture in front of the boy and squeezed his leg, before telling him "good luck with the exams", and exiting the bus.

The victim later mentioned the incident to his mother, who called the police.

Upon his arrest Prior, who makes model aeroplanes and collects old flowers in his spare time, told police: "Oh God, not again."

He recalled the incident but denied that anything sexual took place, admitting only that he may have tapped the victim’s leg as a way of saying goodbye.

Prior has previously committed a number of similar offences and was found guilty of indecently assaulting two young boys in Bushy Park in 2008, but escaped a prison sentence in favour of a community order.

He failed to comply with this order and was given a jail term in 2012 after being found guilty of sexually assaulting an eight-year-old boy.

Judge Paul Dodgson ruled at Kingston Crown Court on Wednesday, September 3 that Prior represented "a significant risk to the public", and that he would serve a jail term in addition to an extended sentence.

Upon hearing his sentence, Prior exclaimed to the judge: "I honestly believe I will not do anything like this again, and am not a danger to the public."

Judge Dodgson replied: "I disagree."