Recent technological developments mean that it is time for a fresh look at the law of private airspace. In future your online purchase could be delivered by a drone. Even today it is easy to buy a toy-sized remotely-controlled helicopter capable of overflying property, hovering in gardens and outside windows and sending back real time video. Just enter “toy helicopter camera” into your favourite search engine and see what there is. But can your neighbour just buy a toy helicopter with a camera and use it to take a closer look at your home or business?  
In Scotland, the vertical boundary of landownership is from the sky to the centre of the Earth (a coelo ad centrum). In 1977 the High Court of England & Wales held (in Bernstein v. Sky Views and General Ltd) that the practicalities of modern aviation made it necessary to “restrict the rights of an owner in the airspace above his land to such height as was necessary for the ordinary use and enjoyment of his land and the structures upon it, and to declare that above that height he had no greater rights in the airspace than any other member of the public.”. But in Scotland the old rule of unlimited airspace ownership is considered still to be the common law (See Professor Kenneth Reid – The Law of Property in Scotland). The landowner’s rights are limited only to the extent that specific legislation applies.     
The (UK-wide) Civil Aviation Act 1982 denies the landowner any remedy for “trespass” or “nuisance” “by reason only of the flight of an aircraft over any property at a height above the ground which, having regard to wind, weather and all the circumstances of the case is reasonable, or the ordinary incidents of such flight.”. The specific legal restrictions on small unmanned aircraft (such as toy helicopters) include: no flights unless the person in charge reasonably thinks it is safe to do so and maintains “unaided visual contact” sufficient to navigate safely. If surveillance kit (a camera) is aboard, more restrictions apply, including the need to stay at least 30 metres away from “any person”, except the craft’s controller, during takeoff and landing (Air Navigation Order 2009). Flying over or near residential premises with an onboard camera may amount to “intrusive surveillance” requiring authorisation under the Regulation of Investigatory Powers (Scotland) Act 2000,  an authorisation that can be given only for police surveillance  for criminal  investigation purposes. Any use of a surveillance camera is also likely to come under the Data Protection Act as there is likely to be other information with which the images can be combined as “personal data”. Passing satellites, whether from the UK or another party to the UN Outer Space Treaty, are dealt with by the Outer Space Act 1986.  
A mix of very ancient and very modern laws should help protect you from prying toys.