Born in St Petersburg, Sanders was educated in England and first worked in the textile business in Manchester and as a tobacco salesman in South America. He began on the English stage in revue and as a radio actor before entering films, going to Hollywood in the mid-30s, where his first role, in Lloyd’s of London, typed him as an elegant bounder. He also played the title role in the film series The Saint, which he regarded as the nadir of his career, and in its successor, The Falcon, before being replaced by his brother, Tom Conway.
He put his name to two ghost-written mystery novels of the 40s, one of which formed the basis of the 1954 film The Unholy Four / The Stranger Came Home. His four wives included actresses Zsa Zsa Gabor (1949-54), Benita Hume (1959-67) and Magda Gabor (1970-71). After his film roles, and his interest in them, declined, and business ventures went wrong, he committed suicide.