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 Liverpool Street station up to 8 times per hour. The journey to London takes about one hour. A number of other airports also serve the London area. The following are mainly used by general aviation flights. Airports are listed at their current borough, although the area may have been outside London at the time of construction. There were several Royal Air Force stations in London. This list excludes those that are classed as non-flying stations. Station are listed at their current borough, although the area may have been outside London at the time of construction. Due to London's high capacity,