This is the moment a man casually pointed a gun at a cashier inside a bookmaker and demanded they hand him over money.
The armed robber lefty the bookmaker in Court Parade, Wembley empty-handed after the cashier refused his demands on 4 June.
Detectives believe the same man successfully robbed a bookmaker in College Hill Road, Harrow days earlier on 31 May.
He loitered inside for up to 30 minutes and then pulled out a note, before demanding the cashier empty the drawers of money.
CCTV shows the man was holding what appeared to be a firearm, say police.
The man police are hunting is described as a light-skinned black or Asian man, possibly mixed race and has a greying beard.
He was dressed in a high visibility jacket and had dark trousers that were heavily covered in paint. He also wore a blue and white striped woolly hat.
Anyone with information should call police on 020 8785 8655.