There has been rapid growth in the availability and use of small-scale drones in recent years, driven by the private benefits available to the drone operator. For a recreational operator the motivation may be enjoyment, but for the commercial operator there is the ability to gather information at lower cost and lower risk than previously possible, and potentially to gather information that could not previously be gathered in a cost-effective manner. Drones also give rise to a number of costs, most notably safety-related and privacy-related, which by their nature are borne by third parties. A mechanism is required for the drone operator to internalise these costs if efficient use of drones is to be achieved.