Police are seeking a Good Samaritan who thwarted a robbery.
At about 6pm on January 10 a 39-year-old woman from Ongar was mugged by two men for her iPhone and the keys for her red BMW.
The men had struggled with the woman in Buckhurst Hill station car park after she initially refused to hand over the keys.
As the men were reversing the BMW, another motorist entered the car park, and seeing what was happeneing, got out of his car and climbed into the passenger seat of the BMW.
The two men then ran off and got into a dark blue car waiting for them in the car park.
The muggers are described as Asian men in their late teens or early 20s, wearing jeans and dark hoodies with the hoods up.
The man who intervened in the robbery left the scene before police arrived, and detectives are keen to speak to him.
Anyone with any information, or the Good Samaritan himself, is asked to contact PC Paul Burnett at Loughton CID on 101.