A striking example from 1941 (update courtesy of David Bownes: 1937) promoting the attractions of Kew Gardens. The poster stresses the frequent electric trains operated by the Southern Railway. Clearly an attempt to maintain some sort of normality and to promote healthy leisure pursuits even in wartime.
The poster is the work of Rojan (Feodor Stepanovich Rojankovsky (1891-1970)), a Russian émigré illustrator of children's books and erotic literature!
The poster quotes from John Milton's early poem L'Allegro:
Towers and battlements it sees
Bosom'd high in tufted trees
The poster was printed, I believe, by The Baynard Press (if you can confirm that, I'd appreciate it).
Keywords: Southern Railway; poster; 1937; Rojan; Feodor Stepanovich Rojankovsky; John Milton; L'Allegro; Kew Gardens; Southern Electric; Russian émigré