Motorists may hold the key to capturing a sex attacker, police have said.

A 27-year-old woman was grabbed from behind during the attack in a layby off the A338, near Wantage, on Sunday, February 1.

During the 15-minute ordeal the attacker smashed her face repeatedly into the ground causing severe bruising.

Det Sgt John Pennycook, of Abingdon CID, said: “This was a violent and serious attack.

“But during the ordeal the victim saw a number of cars pass the location where the attack was taking place.”

The woman accidentally got off the N31 nightbus from Oxford to Wantage at East Hanney and began walking towards Wantage, Det Sgt Pennycook said.

At a roundabout near The Volunteer pub and Williams F1 base, a man in a small people carrier, possibly a green Vauxhall Zafira, offered her a lift but she declined.

She carried on walking until she got to the layby, opposite the Oxford Lane turning to Grove, where she was attacked.

He added: “At this point the victim was grabbed from behind and forced to the floor.

“The victim was then subjected to a serious sexual assault which lasted approximately 15 minutes.

“The victim suffered head injuries as a result.”

Each time the woman tried to turn her head, the attacker smashed her face against the ground leaving her with a bruised cheekbone, eye and jaw, Det Sgt Pennycook said.

He added: “We are appealing for any witnesses that saw the lady in the early hours of Sunday morning or anyone walking along the A338 at that time to contact me.

“I am particularly interested to talk to the male driver who stopped and spoke to the lady.

“It is a very nasty attack but very, very rare.”

Anyone with information should call police on 08458 505505 or Crimestoppers on 0800 555111.

mwilkinson@oxfordmail.co.uk