Cambridgeshire police said the incident happened on Sunday (December 30) at around 6.30pm and was reported to officers later that evening. The victim, a woman in her 40s, was walking along the alleyway in Huntingdon when she was grabbed from behind and sexually assaulted. The attacker was described as having tanned skin, was 6ft tall and may have had long hair. Police said officers have spent the past three days making enquiries, including carrying out searches of the area. As a precaution patrols have been increased in the area. Det Insp Liz Mead said: I am keen to hear from anyone who was in the area of the college during the early evening on Sunday who noticed anything unusual or suspicious. At this stage we are treating this attack as an isolated incident although patrols have been increased as a precaution and I would advise people to take the usual common sense steps I would expect them to take every day. We continue to work closely with the victim to establish all the details of what happened during the incident. INFORMATION: Anyone with information is asked to call police on 101 or Crimestoppers, anonymously, on 0800 555 111.