Hillary Brooke was an actress who is best remembered today for her role on "The Abbott and Costello Show" tv series in the 1950s, as the beautiful blonde resident of the boarding house in which the title characters lived. Second to that show, she was also a leading player in three "Sherlock Holmes" features in the 1940s.
Ms. Brooke appeared in many features of the 1940s and 1950s, and made many tv guest appearances throughout the 1950s.
I wrote to Ms. Brooke in 1981, sending her two photos, to her home in Bonsall, California. She promptly signed and returned them within two weeks. They can be seen here and here. The latter is actually a character portrait from the 1953 sci-fi movie "Invaders from Mars", hence the stern look.
Below is a character pose from an unidentified movie.