The incident at around 4.25pm on Monday at Goldsmiths Jewellers
The main pictured asked to view two watches. Once the shop assistant had taken them from the cabinet, the man grabbed them from the viewing table and ran out of the shop.
Investigating officer PC Jonathan Holt, based at Milton Keynes police station, said: “I am keen to hear from anyone who recognises this man as I believe he may have vital information about this offence.”
If you have any information, please get in touch by calling 101. You will need to quote reference number 431803846
