12inch x 18inch Poster The London Underground (also known as the Tube or simply the Underground) is a public rapid transit system serving a large part of Greater London. This Zoo / Aquarium poster was used to promote travel and improve ridership. Art by George Sheringham (13 November 1884 ? 11 November 1937), a British painter and theatre designer. Published by Underground Electric Railway Company Ltd, 1924 There is a border around the image. The image size is correct.