Land Rover noted that new legislation required that a vehicle's tax disc "must be displayed within parameters that do not exceed 10 degrees". This legislation had been introduced because of Traffic Enforcement officers who were suffering from Repetitive Neck Strain (RNS) from looking at sharply angled tax discs all day.
In order to make sure all Land Rover owners complied with the law, Land Rover had developed a "self-levelling tax disc holder" that always kept the tax disc at the legally required angle. The holder employed "Contra-Motion technology" to achieve this.
(For those outside the UK, the "tax disc" is the vehicle license that must be on the left side of the windscreen.)