Vivian Marshall
Ms. Marshall had only a small handful of movie and TV credits, but I thought she added a great presence to Women's Prison. I loved her impressions of Bette Davis, Tallulah Bankhead, and Ida Lupino, and had to find out more about her.
Googling her name and "singer" brings up a Billboard review from July 11, 1942, of a vaudeville revue called Blackouts of 1942 featuring a novelty singer named Vivian Marshall who does one number in the style of Helen Morgan and Sophie Tucker, and reappears later in the show as "a tipsy soprano botching up an operatic aria."
https://books.google.com/books?id=DwwEAAAAMBAJ&pg=PT4&lpg=PT4&dq=vivian+marshall+burlesque&source=bl&ots=nmTDm-C7Ai&sig=RualQWBKmKpS0A-Ax5HqeGNPpBI&hl=en&sa=X&ved=0ahUKEwi3usHo2NXKAhXM7yYKHZuvCU4Q6AEIMzAE#v=onepage&q=vivian%20marshall%20burlesque&f=false
Another Billboard night club reviewer from January 11, 1947, for a show at the Biltmore Bowl in Los Angeles is unimpressed with "comedienne" Vivian Marshall's impression of an inebriated opera singer, but is less critical of her musical impressions of Eva Tanguay, Nora Bayes, Fanny Brice, and Sophie Tucker.
https://books.google.com/books?id=fxoEAAAAMBAJ&pg=PT39&lpg=PT39&dq=%22vivian+marshall%22+singer&source=bl&ots=Od8vSqoNna&sig=1w86js86h42rhL6XHaaSSXZvV0E&hl=en&sa=X&ved=0ahUKEwjbzMmh29XKAhVG9x4KHZx7D_YQ6AEIPjAG#v=onepage&q=%22vivian%20marshall%22%20singer&f=false