Wiltshire Police are appealing for witnesses following a robbery which happened outside McDonald's, Winchester Street, on Monday (2nd December).
In a statement, Wiltshire Police said, "At around 4pm, a known suspect pinned someone against a pillar and stole cash from their pockets.
"A 12-year-old boy has been arrested in connection with the incident and he remains on bail pending further enquiries.
"There were a lot of people in the area when this incident took place and we believe part of it may have been recorded on a mobile phone.
"Anyone with phone footage or knowledge of this incident is urged to contact 101 quoting crime reference number 54240142319."