A 64-year-old woman had £770 stolen from her while playing on a games machine in a gambling centre.
Police have released an image of a man they are hunting in connection with the theft.
He is described as being white, between 30 and 40 years old, and of slim build with short dark hair.
The woman was playing on a gambling machine at a Cashino branch in Sutton High Street on Tuesday, August 19.
The theft is thought to have taken place between 10pm and 1.10am the following day.
If you have any information, call Sutton police on 101 quoting ref no: 4008723/14.
You can call Crimestoppers anonymously on 0800 555 111.