Ethel Lilian Voynich was the girlfriend of Sidney Rosenblum, otherwise known in Britain as "Sidney Reilly" or "Reilly Ace of Spies." With Rosenblum's last £300 the couple went off to Italy. Here under the Mediterranean sun and under the influence of the Roman Catholic religion, which touched every facet of Italian life and awoke emotionally charged memories of his Catholic upbringing, Sidney bared his soul to his mistress.

She is best known for her first novel, The Gadfly. In Russia, the name of Ethel Lilian Voynich is bracketed with Shakespeare and Dickens as being amongst the greatest writers.

She later married a Polish revolutionary who fought for Poland's freedom from Russian rule and died in New York in 1960 at the age of ninety-six.