DETECTIVES investigating an alleged attempted rape have appealed for a specific witness to come forward.

A CCTV image captured the man Thames Valley Police want to speak to.

Detective sergeant Nathan Lampard said: “We wish to make it very clear, that the man in this image is not a suspect nor he has committed an offence.

“We believe he may have witnessed the incident, which occurred in the early hours of Thursday, July 5, and this man could therefore have crucial information.

“I would like to appeal to him to come forward and speak to police "

The appeal follows an incident where a woman was dragged into Union Street and sexually assaulted.

A man has been charged in connection with the offence.