In the 1910s, Maugham began her interior design career as an apprentice under Ernest Thornton-Smith for a London decorating firm learning there about the intricacies of furniture restoration, trompe-l'œil, curtain design, and the mechanics of traditional upholstery. In 1922 at the age of 42, Maugham borrowed £400 and opened her own interior decorating business at 85 Baker Street, London in 1922. As the shop flourished, Maugham began decorating, taking on projects in Palm Beach and California. By 1930, she had shops in London, Chicago, and New York.