A pervert’s indecent act almost three decades ago has resulted in a four-year jail sentence.

Derek Stringer denied the sordid behaviour while on holiday in a caravan in Leysdown in 1987, but was convicted of indecent assault in September by a jury.

The 67-year-old, of Stratton St Margaret, Swindon, Wiltshire, continues to maintain his innocence, a judge at Maidstone Crown Court was told.

The prosecution alleged Stringer forced the 10-year-old boy to touch his private parts and perform a sex act on him.

The boy told his mother but she was unable to take it seriously because of her medical state.

Recorder Simon Taylor QC said the abuse ate away at the victim over the years and his wife eventually persuaded him to contact the police in 2013.

The judge heard that Stringer had no previous convictions and had not offended since.

Orla Daly, defending, submitted a suspended sentence could be imposed.

“This is an extraordinary case of an isolated, one-off incident some 30 years ago,” she said. “It lasted a short time.”

It happened, she said, while Stringer was drunk and grieving over the death of his long-term male partner.

Stringer’s computer and mobile phone were examined and there was no hint of any interest in young boys.

“The question is whether it is right to impose a custodial sentence 30 years after the event on someone who has not been in trouble since,” said Miss Daly.

“I ask what it would achieve at this stage after such a long period of good character to impose an immediate custodial sentence, despite his denial.

“You are not dealing with someone who is cunning and predatory. The probation service recommends he can be dealt with by a suspended sentence.

“He doesn’t fit the criteria for a sex offender programme, but he is someone who can be worked with. What would be far more productive is an intensive programme.”

But Recorder Taylor said only immediate custody would meet the gravity of the offence.

Stringer’s name will appear on the sex offenders’ register indefinitely and he will be barred from working with children and vulnerable adults.

Investigating officer Det Con Richard Brown said: “The victim in this case should have been able to trust Stringer, who instead abused that trust for his own sexual gratification.

“He forced an innocent child to do something awful against his will, which has had a profoundly negative effect on his life ever since.

“I would like to pay tribute to the victim for having the courage to come forward, and for his continuing strength and determination throughout the investigation and trial.

“I would also like to praise his wife, who has stood side by side and been his supportive rock throughout.

"I hope this case sends a message to all other victims that Kent Police takes all reports of historic sexual abuse seriously and will thoroughly investigate all allegations, no matter the length of time that has passed since the incident occurred.”

Recorder Taylor said a pre-sentence report referred to Stringer’s distorted view on sex.

“It is important this is a once only offence,” he said. “It has had a very serious effect on your victim. It ate at him for years.

“I have to bear in mind it is a historic offence. There is an impact statement from him and his wife. He says it made him shy and introverted.

“He says it has affected him daily for 28 years. It is clear he was still deeply affected by what happened to him all those years ago.

“It is clear there has been severe harm to your victim and it has affected his psyche and personality.”

The judge said the victim was particularly vulnerable because of his personal circumstances.

In continuing to maintain his innocence, Stringer was demonstrating a total lack of empathy for the victim.

“I have to bear in mind what you did has had a significant effect on him - something appalling you did all those years ago,” added Recorder Taylor.