London Heathrow Airport is switching runways in use due to emergency traffic.
The airport announced tonight there is emergency traffic operating in the area.
Since 18:35 local time, the airport dealternated the runways in use.
Landings are now on the northern runway (27R) and departures are on the southern runway (27L).
UPDATE 17:55 London time
A MET Police helicopter is currently circling over Hounslow Heath less than 150 ft. It is a local nature reserve in the London Borough of Hounslow and at a point borders Richmond upon Thames.
UPDATE 19:10 London time
The police helicopter is leaving the area.
UPDATE 19:20 London time
London Heathrow will resume normal alternation at 19:40L, landing on the southern runway (27L) and departing on the northern runway (27R).
This immediate effect will last for the duration of the incident.