David Hughes was found guilty of six offences including indecent assault, gross indecency, sexual assault and allowing a child to watch a sexual act.
The 64-year-old, pictured, was found not guilty of six further offences.
Hughes will now serve 10 years in prison and be placed on the sex offenders register for life, police revealed today.
The offences were committed between 1990 and 2017 and involved two victims.
Investigating officer Detective Sergeant Rich Dickinson said: “Hughes’ actions were deplorable, and have had a lasting impact on his victims. It is absolutely right that he has been served a substantial custodial sentence.
“I would like to take this opportunity to praise his victims who have been so very dignified throughout the investigation, despite the horrifying experiences they were subjected to.
“Hughes has always denied the allegations against him, showing no remorse or acknowledgement of his crimes.”
Det Sgt Dickinson added: “It is vital that any victim of child sexual abuse feels that they can speak out about what has happened to them. As a police force we will investigate all reports and have specially trained officers and partner agencies who can offer support and advice.
“I’d also like to encourage anyone who has concerns about a loved one, friend, relative or family member to also speak to us. Your call could help safeguard or protect someone else and it could help us bring offenders to justice.”
Hughes was sentenced at Sheffield Crown Court on Wednesday April 21 following a one week trial.