Police say the car parked outside the TA barracks near Sutton was an abandoned vehicle. Cordons and restrictions are now being lifted around the scene.
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Homes have been evacuated as the Army works to defuse an unexploded World War II bomb discovered near Wembley Stadium.
The strike threat came just minutes after a national rail strike planned for Monday was called off.
These breathaking views were taken from a helicopter high above the capital.