[1] Wishing to become more politically active and feeling betrayed by Ramsay MacDonald's "defection", both Noreen and Clive Branson joined the Independent Labour Party in Chelsea in Autumn 1931.

While conducting political work in run-down housing blocks, she became more aware of the poverty which existed under British capitalism, and came face-to-face with issues such as unemployment.

[1] In 1935 she attended the 7th World Congress of the Communist International in Moscow and spent several months as a comintern messenger to underground parties in Europe without being caught.

[5] In early 1938 Noreen's husband Clive joined the International Brigades to fight against Nazi backed nationalist forces in the Spanish Civil War, however he was captured on the 3rd of April and was kept prisoner for 8 months.

Inspired by her work as an air raid warden, her husband Clive included Noreen's likeness in his painting Bombed Women and Searchlights (1940)[7] which is currently held by the Tate art museum in London.

[5] Noreen's home city of Battersea soon became a key target for German V1 and V2 rockets due to the presence of its close network of railway tracks and power station.

[5] In 1944, Noreen's husband Clive Branson was killed in Burma by the Japanese when he was hit by an anti-tank shell near Point 315 at the end of the Battle of the Admin Box.

[3][5] After the death of James Klugmann, Noreen Branson took over the authorship of the official History of the Communist Party of Great Britain, adding volumes for the years 1927–41 and 1945–51.