A security guard transporting money in Pinner was robbed at knife point late last night.
The box of cash was swiped from the guard who was carrying it from his security company van to the Abbey National bank in Bridge Street at around 10.30pm.
The suspect, who donned a black balaclava, black coat, gloves and jeans, demanded the cash and threatened the employee with a knife, before running off through the gates at the side of the bank.
No one was injured in the incident put the Flying Squad are encouraging witnesses to come forward.
Anyone with any information should contact DC Pat Dunne on 0208 358 1751 or Crimestoppers anonymously on 0800 555 111.