On Friday last week, a man, who may have been called Andy, offered a lift in a car to two women, aged 18 and 20.
He dropped the women off in High Street, Crowthorne, between 7pm and 8pm and while he is not a suspect, police believe he may have vital information for them as they investigate allegations of rape.
Detective Sergeant Peter Wall, from Maidenhead Force CID, said: “The man in the vehicle is not a suspect and is believed to have been a helpful member of the public who gave a lift to assist two young women.
“He is also a potential witness, but may not be aware of this, and we would like to speak to him to help with our investigation. I would appeal to him to come forward and speak to police.
“This investigation relates to sexual offences which are reported to have taken place on Friday.”
Neither a description of the vehicle nor its driver are available.
Three men, aged 31, 29 and 26 have been arrested and bailed on conspiracy to rape in connection with the allegations. The 31-year-old and 29-year-old were bailed until Monday and the 26-year-old was bailed until Tuesday.
Anyone with any information about the witness or who think they can help the investigation should call 101 or Crimestoppers anonymously on 0800 555 111.