George Butterfield was sentenced today at Leeds Crown Court for a series of sexual offences in the 1990s.
He pleaded guilty to 10 offences of indecent assault against a single victim between 1992 and 1999.
Butterfield, 70, of Halfpenny Lane, Pontefract, was also made the subject of a sexual harm prevention order.
West Yorkshire Police began an investigation after his victim came forward to report the offences in early 2017.
Speaking after the sentencing, Det Insp Vanessa Rolfe said: “Butterfield committed multiple sexual offences against a young and vulnerable victim over an extended period of time and thoroughly deserves to be behind bars.
“His victim has had to live with the knowledge of what he did to her into her adult life and has shown a great deal of courage in coming forward and making sure Butterfield has been made to answer for what he did.
“We hope this case again demonstrates that police will always work to seek justice for victims wherever possible, even when the offences are not recent.
“I can promise victims that all sexual assault reports will be thoroughly and sensitively investigated by specially trained staff.”