A woman was “strangled and had her head slammed into a wall” in a mugging by a man said to have been dressed as a delivery driver.
The victim, in her twenties, was attacked at about 2.15pm last Thursday in Heath Lane in Blackheath, where homes can fetch £3 million.
Witnesses said the assailant fled with her handbag. Police found the victim with a minor head injury.
The attacker had been waving to children in the road moments before the incident, according to one witness.
She posted to Facebook: “A poor lady who was waiting for a friend was physically attacked, strangled and had her head smashed against a wall. The man then ran off with her handbag claiming she was attacking him.
“The police and ambulance arrived within minutes and attended to the victim. Just want to warn others in the area to be vigilant.
“I was with children and this man walked past me smiling and waving to them not minutes before he attacked the lady.”
She added: “I left her with the police and paramedics. She had quite a bump on her forehead and marks around her neck. But a truly brave woman, she chased the man up the hill shouting and screaming.”
Police are investigating and UPS has launched its own investigation after it was alleged the suspect was wearing one of its uniforms.
A spokesman said: “UPS is taking this matter extremely seriously and is co-operating fully with the authorities.”
A Met spokeswoman added: “Officers attended and found a woman, aged in her twenties, with a minor head injury. It was reported that she was assaulted by a male suspect who then took her bag and left the scene.
“Enquiries are ongoing; no arrests have been made.”