History of the London Underground to determine the cause. Following the incident, a system that stops a train automatically if the driver fails to brake was introduced at dead-ends on the London Underground. The Northern City Line was connected to British Rail tracks at Finsbury Park in the 1970s. The last tube train ran in October 1975, and British Rail services began in 1976. In 1977, the Piccadilly line was extended from Hounslow to Heathrow Airport, and in 1986 a platform serving Terminal 4 opened on a loop line. The Fleet line through central London was first proposed in 1965, taking over the Bakerloo line's
Airports of London Airports of London The metropolitan area of London, England, United Kingdom is served by six international airports and several smaller airports. Together, they make the busiest airport system in the world by passenger numbers and the second-busiest by aircraft movements. In 2016, the six airports handled a total of 163,231,321 passengers. The London airports handle 60% of all the UK's air traffic. The airports serve a total of 14 domestic destinations and 396 international destinations. Located in the London Borough of Newham, City Airport is situated in London's Docklands, and is the closest to central London, which limits its size