A man wearing a dressing gown and slippers sexually assaulted a woman in an alleyway.
The victim, in her 20s, was approached by the attacker near the Co-op store in Upshire Road, Waltham Abbey, at 7.15pm.
She was then groped in a nearby alleyway by the man, who was wearing a navy dressing over his clothes, before he ran off.
The attacker is described as white, 5ft 9ins, with dark brown hair. He had very pale skin and is believed to be in his 30s.
Anyone with information about the incident, which happened on Decmber 28, is asked to contact PC Danielle Brennan at Loughton police station on 101 or Crimestoppers on 0800 555 111.