Throughout the 20th century, the artistic merit of advertising was much debated thanks to the increasing presence of posters and signs in London's public spaces. Frank Pick, the managing director of London Transport, did much to raise the standard of poster design in London in the first half of the century. Under his regime, London's Transport posters were invariably artistically interesting, clever and striking. The Central School of Art and Design was one of many London art schools that treated poster design as an important part of the training they provided. Posters by Central students were exhibited at the Royal Academy in the 1920s and the British Pavilion of the International Exhibition of Decorative art in Paris in 1926.

One of the sites that excited most controversy in relation to public advertising was Piccadilly Circus. Electrically lit advertisements had arrived by 1910 and, to some, seemed tawdry and gimmicky. The London County Council (L.C.C) tried unsuccessfully to exert some control over the quality of the flashing adverts, but eventually gave up. For the first half of the century the dominant adverts in Piccadilly Circus were for Bovril and Schweppes, both British firms; by the second half, Coca-Cola and other multinational firms had taken over.

The L.C.C. also failed to prevent adverts intruding into London's landscape at the Oxo tower on the south bank. Designed in 1929, the tower worked around the prohibition on large-scale electric adverts by incorporating the advert into the fabric of the building. Its topmost windows formed the letters OXO, spelling the name of the meat-extract product made by the firm that owned the wharf beneath.