Dear Professor Rodgers,
I too have been very interested in Audrey Lucas. Did you read her biography of her father, E. V. Lucas? It is readily available online and includes photos. She also worked for the BBC later in life, and so that might be worth an enquiry like you said. She volunteered with the Red Cross in France in World War I with her mother, Elizabeth Lucas, in the hospital that JM Barrie helped establish there and her father also supported, I believe.
Elizabeth Lucas' letters are held at Beinecke Library of Yale University and so may be worth checking out.
E. V. Lucas was a member of various clubs in London, and of course the editor of Methuen Publishing, and a contributor to Punch. So those might hold clues as well.
Have you published your work on Audrey Lucas anywhere? I'd be curious to read it.