His mother was Caroline (1834–1921), youngest daughter of Edward Horwood of The Manor House, Weston Turville, Buckinghamshire.
In the 1880s he was based in Brăila in Romania, where, in July 1885, his younger brother Charles Leader Justice Stuart drowned in the Danube at the age of 16.
Stuart had been named Japanese consul but his appointment was deferred owing to the outbreak of the Russo-Japanese War.
At about 11 p.m. on 20 May 1906, Stuart was returning to his home at Makhinjauri, 5 miles north of Batum, after dining with a friend, when he was shot three times from behind a tree.
Letters and memoranda were exchanged by Elihu Root (United States Secretary of State, George von Lengerke Meyer (US Ambassador to Russia), Whitelaw Reid (US Ambassador to the UK), Cecil Spring Rice (British Chargé d'Affaires at Saint Petersburg, and author of the lyrics to the hymn I Vow to Thee My Country), Patrick Stevens (British Consul at Batum), Alexander Petrovich Izvolsky (Russian Foreign Minister) and Baron Roman Romanovitch Rosen (Russian Ambassador to the US).