sentences:  During the late 1930s, the British government had been studying the future of air transport and airports in the London area.It had been decided that London would be served by four airports - Croydon, Heston, and new airfields at Fairlop in Essex and Lullingstone, Kent.To this end, improvements and extensions had already begun at Heston, with the intention of bringing it up to the most modern standards of airports elsewhere in Europe.