British Airways Cityflyer, also styled BA CityFlyer, is a British regional airline, and a wholly owned subsidiary of British Airways with its head office based in Harmondsworth, in the London borough of Hillingdon. It operates a network of domestic and European services from its base at London City Airport. All services operate with BA's full colours, titles and flight numbers. BA Cityflyer Limited holds a United Kingdom Civil Aviation Authority Type A Operating Licence, meaning that it is permitted to carry passengers, cargo and mail on aircraft with 20 or more seats.