A woman admires a poster from 1910 entitled 'Too Much Of A Good Thing' by John Henry Lloyd in the exhibition 'Poster Art 150 - London Underground's Greatest Designs' in the London Transport Museum on February 12, 2013 in London, England. The exhibition celebrates 150 years of the London Underground by showcasing 150 posters from the Museum's archive of over 3,300. The exhibition opens on February 15, 2013 and runs until October 27, 2013.