I expect this thread will have attracted the attention of a fair number of sensible model aviators so the following may be of interest:
Drone ban over London and Windsor during Obama visit
Drones will be banned from flying between 9pm on Thursday (21st April I guess) and 10.30am on Sunday over a large part of London, from Purley in the south to Haringey in the north.
Restrictions are in place for the skies between Windsor and London on Friday - when the Obamas will join the Queen for lunch at Windsor Castle the day after her 90th birthday celebrations - and between Stansted airport and London on Thursday night and Sunday morning.
The regulations prohibit aircraft - including drones - from flying below 762 metres (2,500 feet) within the specified areas unless they are using Heathrow, Stansted or London City airports, London Heliport, RAF Northolt or are being operated by the emergency services.
Pilots of other aircraft wanting to fly in the restricted areas must seek permission from the Metropolitan Police.