Marion Smith (née Lehrburger) was born to prosperous, assimilated parents in Bogenhausen, Munich. Her father helped run the family factory; her mother was originally from Berlin. In the 1920s Marion and her family moved to Berlin, where she was educated at a good secondary school, and did not experience antisemitism before 1933. In the 1930s she worked as a sales assistant and spent a period in Prague, where her brother Egon Larsen (Lehrburger) was a journalist.
Marion emigrated to Britain in September 1938 on a permit for domestic service, although she disliked this type of work. During and after the war she worked for the Foreign Office (Political Warfare Executive) on the re-education of German prisoners of war. She married Lewis Smith, a British Jew originally from an Orthodox East End background, and they lived in North West London. Marion taught evening classes in German at college.