From February 1921 to 1929 Lucas was married to the novelist E. B. C. Jones (1893–1966), known as "Topsy" to her friends. She was the sister-in-law of his former supervisor at Trinity, Donald Robertson; he got to know her after reading and admiring her first novel, "Quiet Interior" (1920). Jones dedicated two novels to Lucas and based two characters on him – Hugh Sexton, gassed in the War, in "The Singing Captives" (1922), and Oliver in "The Wedgwood Medallion" (1923), a Cambridge classics graduate now studying the Elizabethan drama. Lucas based the character Margaret Osborne in "The River Flows" (1926) on her – a semi-autobiographical first novel that shifts some of his experiences of 1919–1920 to 1913–1915. The character Hugh Fawcett ("the best brain in the Foreign Office" but not much use as a matchmaker) was based on Keynes. Through the Apostles Lucas was associated with the Bloomsbury Group, Virginia Woolf describing him to Ottoline Morrell as "pure Cambridge: clean as a breadknife, and as sharp". To Lucas, interviewed in 1958, Bloomsbury had seemed "a jungle":