Main Line opened to King Cross in 1852 having used a temporary terminus at Maiden Lane from 1850.
Overground line (the North London Line) opened in the early 1850s and now runs from Richmond to Stratford.
Piccadilly line opened as the Great Northern, Piccadilly and Brompton Railway in 1906, linking Finsbury Park with Hammersmith.
Victoria line opened in 1968.
Originally, the "Circle" lines and the "Widenend" lines platforms at Moogate were mostly in the open air ...
Bur we have left the Northern City line to the last. Presently this carries stopping trains from northern suburbs and Hertfordshire towns on Mondays to Friday only, leaving the main line at Finsbury Park. It is a true "Tube" line running in proper tunnels and sharing Old Street and Moorgate stations with the Northern Line. But it carries full-size "big" former British Rail electric trains.
Meranwhile, yesterday, Sons Nos 1 and 3 took fbb to see the James Bond movie "Skyfall". This featured some tense action scenes on London's Underground at Temple and Westminster stations; plus action on a train going to Richmond. In one scene the baddie creates a crash whererby one of these "District Line" trains plunges through a blown-up hole in the track and on to James Bond. Very painful!
Readers with only limited knowledge of London's tube system will immediately recognise that the trains illustrated in these incidents ...