Firstly all the talk about it being an airfield is wrong, it is private land.
Actually, it is an AERODROME.
Definition of 'Aerodrome' in Annex 14 to the Convention on International Civil Aviation (Chicago 1944):
A defined area on land or water (including any buildings, installations, and equipment) intended to be used either wholly or in part for the arrival, departure and surface movement of aircraft.
Definition of 'Aerodrome' at section 105 of the Civil Aviation Act 1982:
Means any area of land or water designed, equipped, set apart or commonly used for affording facilities for the landing and departure of aircraft and includes any area or space, whether on the ground, on the roof of a building or elsewhere, which is designed, equipped or set apart for affording facilities for the landing and departure of aircraft capable of descending or climbing vertically.
TOO