Walter FLORELL was a custom millinery designer who flourished in the 1940's and 1950's, when a fashionable woman's hats were as important as her clothes. He was born in Hamburg, Germany, the son of an Austrian duchess and a German father. Mr. FLORELL grew up in Berlin. He was a dancer with the Berlin Opera Company and became interested in costume design. In the 1930's he went to London and joined a fashion house. He came to the United States in the late 30's, worked as an assistant designer at Lily Dache and opened his own millinery salon in 1939. In his heyday, Mr. FLORELL designed for a number of famous women, including the Duchess of Windsor, Greta GARBO, Gertrude LAWRENCE, Gloria SWANSON, Hope HAMPTON, Joan CRAWFORD and Bette DAVIS. He also worked on Broadway shows such as ''Harvey'' and ''The Voice of the Turtle'' and on movies such as ''Easter Parade'' and ''Sunset Boulevard.'' He was a courtly man who welcomed clients to his 57th Street salon by kissing their hands. Although primarily a milliner, he also designed hairdos, clothes and furs and is credited with putting Carmen MIRANDA into fruit-filled turbans and cork-soled platform shoes to compensate for her diminutive size. He closed his New York salon in 1963. During his retirement, he concentrated on painting and writing. Then in 1979 he opened a clothing business on Seventh Avenue but was forced to close it a year later because of failing health. He died October 6, 1986 in his house in Wilton, Connecticut.