In response to Vipes -

I haven't looked at the impact of the new runway. It would be for smaller planes providing links between Heathrow and relatively close destinations freeing the main runways for bigger planes. I don't think we would see these planes over here although the ones that do come over us at present would most likely get their slots replaced by bigger planes.

On the subject of airbrakes - Heathrow requires all arriving planes to have a continuous descent at minimum noise effectively from when they leave the hold until they are on final approach. If this is done well by the crew then the plane shoud be virtually gliding down only increasing power again as they lower wheels and flaps when well past us. In practice air traffic restrictions and less skilled pilots may find they need to open the throttles earlier - perhaps when coming over us, in order to limit their rate of descent. I suspect that if you were to watch and listen carefully you would find that BA planes, whose pilots are using Heathrow all the time with the continuous descent aproach, are quieter than many others who only come here occasionally. Airbrakes (as distinct from flaps) are highly unlikely to be used during the flight over London - they are generally only used when it is necessary to lose height quickly from higher altitudes. Almost certainly used by the depressurised Quantas plane making its quick trip into Manilla the other day!