Shener Rutfulla, 34, of Oxford Road, has been charged with allegedly attacking the 21-year-old victim as she was walking away from the town centre along Gatehouse Road at about 1am on Sunday.
The victim, who was walking home from a night out, was grabbed by her shoulders, pushed to the ground and sexually assaulted.
A police patrol was passing the area and the woman was able to get their attention.
Mr Rutfulla was arrested shortly afterwards.
He has been charged with ‘assaulting a female aged 13 and over by penetration with part of a body/thing’.
He has been remanded in custody and is due to appear at High Wycombe Magistrates’ Court today.