The Good Samaritan spoke to the 19-year-old victim about 5am near St Leonard’s Church on Shoreditch High Street on Saturday August 24, 2019.
He came across the victim and a friend outside the church and walked them both to Shoreditch Overground station.
The dog walker is described as white and between 30-40 years old and his dog is thought to be a large, short-haired mastiff type breed.
The Met’s DC Rob Johnston, leading the investigation, said: “This man helped the woman on the night and I am appealing to him to help us now.
“We have previously shared this image at the time and on a number of occasions since but I am renewing this appeal in the hope that the man comes forward as he may not have realised the victim made a report to the police.”
A 23-year-old man was arrested on suspicion of rape five days after the incident but was released under investigation.
If you recognise yourself as the man described or if you have any information that could help the investigation call police on 101 and quote CAD 1551/30NOV21 or tweet @MetCC.