RATP Dev Transit London Limited, trading as RATP Dev Transit London, is a bus company operating mostly in west and south-west Greater London. The London United brand is a subsidiary of RATP Dev Transit London and operates services under contract to Transport for London.

London Buses is the subsidiary of Transport for London (TfL) that manages most bus services in London, England. It was formed following the Greater London Authority Act 1999 that transferred control of London Regional Transport (LRT) bus services to TfL, controlled by the Mayor of London.