where it is warm and bright
In the current Cabinet, themed The Underground, Michael Saler tells the story of how the London Underground became a leading patron for graphic design and art in the 1920s and '30s. Led by Frank Pick, the Tube started commissioning posters from leading artists of the time, resulting in some awesome art-meets-advertising in a wide range of modernist styles.
The examples below are 'London Transport' (1938) by Man Ray, 'Where it is warm and bright' (1924) by V.L. Danvers, and 'Go out into the country' (1938) by Graham Sutherland.
The whole collection is online at the London Transport Museum.