A scarce 1948 ‘Quad Royal’ station map of the Underground by Beck

A poster map for the use at London Underground stations, still designed by Beck, the originator of the 'electric circuit' diagramatic map in 1933. On this issue parts of the District and Metropolitan Lines (both coloured green) are edged with black to mark the 'Inner Circle', which was renamed the Circle Line and coloured yellow a year later. The extensions to the Northern and Central Lines, proposed before the war but abandoned, are still shown.