Detectives have released an e-fit of a robber who threatened a student with a knife.

An 18-year-old was walking in Centre Drive, near an alleyway leading to Epping Tube station, at around 8.25am on Tuesday when was approached by a man with a knife.

He ordered the student, who lives in Epping, to hand over his headphones.

Two men walking nearby saw what was happening and rushed to intervene.

They chased the robber towards the Ivy Chimneys area, but lost him in estate side roads.

Police have appealed for help to find the two men who rushed to the aid of the student as they may be able to provide vital information regarding the suspect.

Investigating officer DC Stephen Baker said: "The two men clearly prevented the student from being robbed and tried to catch the suspect. 

"The student lost sight of the suspect and the two men and continued his journey to college and reported the incident later. As a result we do not have the names of the two men.

"We would like to talk to them as they could give us vital information about the person they chased.”

The robber is described as black, in his early 20s, of athletic build, with a prominent nose. He was wearing a grey hooded top and blue jeans.

Anyone with information should contact DC Baker at Loughton CID on 101 or call Crimestoppers anonymously on 0800 555111.