Manual and powered wheelchairs and mobility scooters are medical devices for those who cannot walk or who have difficulty walking. In law you will still find them called 'invalid carriages'. There are three types of 'invalid carriage' defined in 'The Use of Invalid Carriages on Highways Regulations 1988':
• Class 1 - manual wheelchairs, i.e. self-propelled or attendant-propelled, not electrically powered; • Class 2 - powered wheelchairs and mobility scooters, intended for footpath or pavement use only with a maximum speed limit of 4 mph; • Class 3 - powered wheelchairs and mobility scooters, for use on the road, with a maximum speed limit of 8 mph but with the facility to travel at 4 mph on a footpath or pavement.
Some other types of small electrically powered vehicles such as golf buggies look similar to mobility scooters. They are not 'invalid carriages' within the meaning of the 1988 Regulations. It may be illegal to use them on the public highway.