An early example of the iconic map of the London Underground

A fine example of the pamphlet version of Beck's diagrammatic map of London's tube network, published the year after the first issue. Already the original diamonds for interchanges have been changed to the circles used today; the confusion between the original orange of the Central Line and red for Metropolitan has been clarified by making the Central Line red and the latter brown; the Piccadilly Line has been extended from South Harrow to Uxbridge.
Beck's revolutionary new 'electrical circuit' design dispensed with scale, bearing and surface landmarks other than the Thames, making the stations equidistant and limiting the curves to either 45 or 90?.
Beck submitted two proposals to the Publicity manager before his idea was accepted, and was paid only 10 guineas (today ?380) for the artwork of this card, and 5 guineas more for the poster.