A double-decker bus is a bus that has two storeys or 'decks'. Global usage of this type of bus is more common in outer touring than in its intra-urban transportation role. Double-decker buses are in common use throughout the United Kingdom, and have been favoured over articulated buses by many operators because of the shorter length of double-deckers, and less need to have standing capacity. The majority of double decker buses in the UK are between 9.5 metres (31 ft 2 in) and 11.0 metres (36 ft 1 in) long, the latter being more common since the mid-1990s, though there are three-axle 12 metres (40 foot) models in service with some operators. Double-decker coaches in the UK have traditionally been 12.0 metres in length, though many newer models are about 13.75 metres (45 ft 1 in). The maximum permissible length of a rigid double-decker bus and coach in the UK is 15.0 metres (49 ft 3 in), and although there are no theoretical restrictions on height, coaches are normally built to 4.38 metres (14 ft 4 in) high, while 'highbridge' buses are normally about 20 centimetres (8 in) taller. Articulated double-deckers are also allowed at a maximum length of 18.75 metres (61 ft 6 in).
In 1941, Miss Phyllis Thompson became the first woman licensed to drive a double-deck vehicle in England. She drove for the bus company Messrs. Felix Motors Ltd, then at Hatfield near Doncaster.
The red double-decker buses in London have become a national symbol of England, and the majority of buses in London are double-deckers. Right after the Second World War the first double-decker buses were the AEC Regent II and AEC Regent III models. A particularly iconic example was the Routemaster bus, which had been a staple of the public transport network in London for nearly half a century following its introduction in 1956. Because of cited difficulties accommodating disabled passengers, the last remaining examples in use finally retired in 2005, although Transport for London has established two "heritage routes", which will continue using Routemasters on selected parts of routes 9 and 15. Since 2008, a new Routemaster has been developed and entered service on 20 February 2012, in time for the 2012 Summer Olympics.