Police say the victim was walking through the Memorial Gardens at around 7.45 pm when he was attacked by five men who stole cash and a Cartier watch from him.
The victim, a 20-year-old man from London, managed to run away into the High Street and was later treated in hospital for a wound to his wrist.
Police are appealing to anyone who saw what happened to contact them online quoting serial 1103 of 26/11.