Stephen Shield, 53, of Balmoral Road, Lancaster, has been found guilty of three counts of indecent assault following a trial at Preston Crown Court.
The three historic allegations related to one male victim aged between 17-24 years, the committed between 1985 and 1992.
Sentence was adjourned until December 13th.
Detective Chief Inspector Jo Edwards, of Preston Police, said: “I am pleased that Mr Shields has been convicted of these offences.
“The victim in this case had lived with the knowledge of Mr Shield’s offending for a long period of time; this has had a significant impact upon him. It was a difficult decision for the victim to come forward and I am please that he felt confident enough in the Constabulary to help bring this man to justice.
“The fact that these convictions come a long time after they were committed shows that we will always take any allegations of sexual abuse extremely seriously and will investigate them thoroughly no matter how long ago they happened.
“I would encourage people with any information about sexual abuse or who has been a victim of sexual abuse to come forward and report their concerns confident in the knowledge it will be investigated appropriately and with sensitivity.”