[6][7] Her father was a paper-making engineer, and Marx would later describe his work as a major influence on her interest in mass-produced design and popular art.

[11] As a student, Marx was influenced by Paul Nash, then a tutor at the RCA, who introduced her to publishers and encouraged her avant-garde leanings.

[8] Her work was judged to be "vulgar", reflecting her interest in popular forms and rejection of the traditional definition of fine arts.

[4] In 1925, after leaving school before finishing her degree, Marx went to work for the textile designers Phyllis Barron and Dorothy Larcher at their studio in Hampstead.

[4] Four of Marx's thirteen original designs are known to have been produced as a part of this redesign, including a "shield" pattern that was used in the London Underground for decades.

[8] Unlike her experience with the London Passenger Transport commissions, Marx found the process of collaboration with manufacturers on Utility Furniture textiles to be a successful one.

[17][15][7] During the Second World War, she began writing and illustrating her own small format children's books, including Bulgy the Barrage Balloon (1941) and The Pigeon Ace.

[21][22] During World War II, she was commissioned by The Pilgrim Trust to paint 14 watercolours of buildings under threat from bombing for its "Recording Britain" project.

[17] From the late 1930s Marx and Lambert began collecting popular ephemera, such as scrapbooks, valentines, paper peepshows, children's books, Staffordshire dog figurines and toys.

[15][25] In the introduction to the 1947 book they defined their subject as "the art which ordinary people have, from time immemorial, introduced into their everyday lives, sometimes making it themselves, at others imposing their tastes on the product of the craftsmen or of the machine".

[13] Marx taught a Wednesday design and engraving class at the Ruskin School of Art at Oxford, with colleagues Barnett Freedman, Eric Ravilious and Paul Nash, until 1936.

In 1949 she took an interior decoration lecturer position at the London County Council City Literary Institute in Covent Garden.

[31] In April 2022, English Heritage unveiled a blue plaque in Marx's honour on her former home and studio at 39 Thornhill Road, Barnsbury, Islington, London.