As mentioned, it actually comes from the law of trespass, and possibly any parts of common law that have not been put into abeyance by Act Of Parliament, but local Planning permission is involved, too, although this is slightly off topic. In fact, current planning regulations allow a helicopter to be used for personal, business and leisure uses "as many people use a private car" from the owner's dwelling house without limitation, making it exempt from planning control, provided the use is incidental, or ancillary to, the principal use of the land. Planning Policy Note 24 about Planning and Noise paragraph 18 states that, in general, where helicopters are used from gardens or commercial premises and their use is incidental to the principal use of the land then planning permission is not generally required, but the commonly accepted frequency is that a spot of land can be used up to 28 days in a year witht planning permission being required. There are quite a few spots in the average field......
Phil