London Buses route 21

This is a list of Transport for London (TfL) contracted bus routes in London, England, as well as commercial services that enter the Greater London area (except coaches). Bus services in London are operated by Abellio London, Arriva London, CT Plus, Go-Ahead London (Blue Triangle, Docklands Buses, London Central and London General), Metroline, RATP Group (London Sovereign, London United and Quality Line) Stagecoach London (East London, Selkent and Thameside), Sullivan Buses, Tower Transit and Uno. TfL-sponsored operators run more than 500 services.

Non TfL-sponsored operators including Abellio Surrey, Arriva Shires & Essex, Arriva Southern Counties, Carousel Buses, Go-Coach, First Berkshire & The Thames Valley, Metroline, Metrobus, Red Rose Travel and Trustybus operate services between parts of Buckinghamshire, Essex, Hertfordshire, Berkshire, Kent, Surrey and Sussex on the one hand and London on the other and one local council sponsored service each in the boroughs of Bexley, Barking & Dagenham and Hackney (extending into Islington).

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