A moped gang were chased by weapon-wielding builders after trying to steal jewellery from a woman as she walked a child down a London street.

CCTV of the incident last week was posted by Britain's Got Talent judge Amanda Holden, and shows four people in dark clothing and helmets pull two mopeds into a narrow street off a busy Richmond road.

The two pillion passengers get off the bikes and the four gang members can be seen seemingly plotting their attack out of sight of their target.

Two members of the gang then ride away from the main road and out of shot, leaving two criminals on foot who can be seen waiting to pounce.

As a woman - who is holding hands with a child - walks by, the muggers threaten the unsuspecting victims and try to steal jewellery from the woman.