Do you really need to worry about landing charges?
-Well yes I do, they maybe wealthy but they are not stupid. Its a cost benefit analysis to them, bearing in mind they have helicopters and schedule flexibility is important to them. I believe they would avoid Heathrow if parking costs are more than the Helicopter transfers and/or the alternative airports offers greater flexibility to their schedules. I remember a particular Falcon 900 that would fly from London to Manchester just for the passenger to get on his Airliner.