Outside London, taxis are licenced by the local authority, and in many places are required to be painted a certain colour. Most major cities predominantly use London taxis, again traditionally black but this is not always mandatory. Smaller towns and rural areas allow more varieties of passenger cars, which may require taxis to be painted in a particular livery as a licence condition. A distinctive livery helps improve identification, which in turn improves passenger safety and accessibility, as well as provide a more professional service and create and promote a local identity with taxis a common sight around town. Many towns use two-colour schemes, such as white vehicles with another specific colour on the bonnet and tailgate. The seaside city of Brighton uses white with an aquamarine colour, Windsor, home to the Queen's residence at Windsor Castle, uses white with royal purple on the bonnet and tailgate, and in the East Riding of Yorkshire white with green and Yorkshire rose markings. Basildon taxis display white with orange bonnet and tailgate, Leeds white with black, Cardiff black with white, and West Suffolk and Middlesbrough black with yellow. Bradford are all white with a green diagonal stripe on the front side doors. St Albans are all white with a yellow stripe running the full length of the side, and in Bournemouth they are pale yellow with a white stripe. Single colour schemes include blue in Bristol, teal in Guildford, and silver in Portsmouth, whilst white is used widely including in Southampton, Sunderland and Scarborough. In Hartlepool and Derby taxis are yellow, but both local authorities considered changing the livery in 2019 to reduce costs whilst still allowing taxis to be easily identified. Hartlepool proposed a two-colour scheme with a standard manufacturer colour such as white, silver or black as a base, and retain yellow only on the bonnet and boot, but abandoned plans after a consultation. Derby plans to change to black with a yellow diagonal stripe on each side.