This paper examines the late musical compositions of Dame Ethel Smyth in the context of British society and culture between the two World Wars. It focuses on Smyth's large-scale works, especially her operas The Boatswain's Mate (1914) and Entente Cordiale (1923-1924) and her oratorio The Prison (1930). Using these works as examples of the composer's mature style, I draw attention to a number of Smyth's original artistic choices as well as her sophisticated use of social commentary. Also considered in this research are certain anticipated roles for women as composers at the time, Smyth's other passions and pursuits, and her interactions with her contemporaries. Her activities as a composer reflected an evolving social landscape for British women in addition to new musical developments.