Over the years, Leen was behind over 50 magazine covers and contributed countless reports from around the world, including the story of her dog Lucky which began in 1949 and later led to a book. In addition to her many animal stories, she is remembered for covering young people in the 1940s and 1950s and the group of artists known as The Irascibles. She also documented European royalty, fashion Models, and actresses. From 1973, Leen avidly continued to publish her work in book form, including her notable images of bats which she called her flying kittens.