As a young man, he saved German Jewish activist Liesel Carritt from being deported to Nazi Germany by agreeing to enter into a marriage of convenience.

In 1936, Noel Carritt, his wife Liesel, and his brother Anthony, all joined the International Brigades during the Spanish Civil War and took part in battles against fascist forces led by Franco and backed by Hitler and Mussolini.

[11] He and some acquaintances of his (W. H. Auden and Julian Murray) agreed to enter into marriage of conveniences to stop Jewish refugees from being forcefully deported back to Nazi Germany.

[12] Carritt married a German refugee and communist activist called Liesel,[12] whose father was the former editor of Weimar Germany's main liberal newspaper, the Frankfurter Zeitung.

[13] Although the marriage began as a method to stop Liesel being deported to Germany, the couple appears to have had an affectionate relationship and bonded through their mutual communist political beliefs.

In December 1936, Carritt left his teaching job without notice to join the International Brigades and caught a train to London.

[12] While in Victoria station, he wrote a message to his parents written on the back of a cheque that explained his decision to travel to Spain to join the International Brigades.

[15][12] While visiting a clothing factory in the East End of London, He met a seamstress called Florence Simkins who was working as a shop steward for the Tailor and Garment Workers' Union.

[12] Noel Carritt and his wife Liesel mutually decided to divorce in 1941, before he married Florence Simkins later that same year.

[18] After WWII, Noel Carritt became the Head of Biology at Dr Challoner's Grammar School in Amersham, Buckinghamshire.