Description A man from Stoke-on-Trent has been jailed for 20 years, with an additional four years on licence, after being convicted of child sexual offences.Mark Roberts, 39, of Madison Street, Tunstall, was sentenced at Stoke-on-Trent Crown Court today (Wednesday 13 April).Allegations of abuse against a child were reported to the force and an investigation was launched.He pleaded guilty to assaulting a girl under 13 by touching.He was found guilty of the rape of a girl under 13 and sexual assault of a girl under 13.