By the time Mae West wrote and starred in this bawdy comedy-drama, she was a major box office draw as a result of Sex (1926), which garnered the attention of audiences, critics, and the police. Similarly, her follow-up play, The Drag, which featured homosexual characters, met with so much controversy that it closed out of town. In Diamond Lil, which opened on 9 April 1928 at the Royale Theatre for 176 performances, West effectively balanced the play's risqué elements with humor and melodrama, a formula which served her well in a string of 1930s motion pictures she scripted and starred in beginning in 1932.
Lil is the prototype of West's screen persona, a sexually liberated, good-hearted 1890s adventuress from the "wrong" side of town who lives by her own code in a man's world. Despite her involvement with the unfaithful, two-fisted Gus Jordan, owner of a Bowery saloon and a white slave trafficker, Lil develops relationships with other men. Among them is Captain Cummings, a policeman in disguise as a Salvation Army preacher, who ends Jordan's white slave trade while protecting Lil from involvement. Drawn to Cummings, Lil contemplates "reforming." West toured with the play and revived it in London in 1947 for a year-long run that inspired her to bring it back to Broadway in three limited engagements between 1949 and 1951.
The Historical Dictionary of the American Theater. James Fisher.