Sir John Randolph Leslie ('Shane'), third baronet, of Glaslough, county Monaghan, was born on September 24, 1885 at Stratford House in London. He was the eldest of four sons born to Sir John Leslie, second baronet, and his wife, Léonie Blanche, youngest daughter of Leonard Jerome of New York. Leslie spent his childhood in Ireland. He was educated at Eton College and later at King's College, Cambridge. While at Cambridge he converted to Roman Catholicism and became a passionate Irish nationalist. It was then that he began to use the Irish form of his name - Shane.

After graduating in 1907, having affronted the Anglo-Irish Protestant ascendancy into which he was born, he traveled to Russia and stayed with Leo Tolstoy at Yasnaya Polyana. While in Russia he was influenced by many social theories.

Leslie was also the first cousin of (Sir) Winston Churchill, whose mother Jennie Jerome Churchill was a sister of Leslie's mother. Churchill showed interest in his cousin's political endeavors and introduced him to John Redmond, the leader of the Irish Nationalists in the House of Commons. Redmond convinced Leslie to run in Londonderry as a Nationalist in the 1910 election. He did not win the seat and after the election moved to America, where he worked with Bourke Cockran, the Irish orator, who was a friend of Churchill's. Together they sought to ease the hostility of American Irish toward the English.

In 1912, while still in America, Leslie married Marjorie, the youngest daughter of Henry Clay Ide, judge of the Vermont Supreme Court and later governor-general of the Philippines.

Sir Shane's brother Norman, a captain in the Rifle Brigade, was killed in World War I. Leslie was attached to a British Ambulance Corps during the war until he became ill and was placed in a military hospital in Malta. Here he wrote his first major book, The End of a Chapter, and published it in 1916.

Between 1916 and 1917 Leslie worked in Washington with the British ambassador, Sir Cecil Spring-Rice, who was urging the United States to declare war against Germany. Leslie published a magazine entitled Ireland and worked with Spring-Rice to establish understanding between Westminster and Washington.

One of his boldest political moves was to implore the British politicians not to execute the leaders of the 1916 Easter rising in Dublin. Unfortunately his pleas went unheeded and sixteen outstanding Irishmen were shot, undermining the work he was doing to ease Anglo-Irish relations.

He became a fluent writer and a member of the Irish Academy of Letters. In the remainder of his life he published some forty volumes which included poetry, novels, short stories, memoirs, biographies and nonfiction of various kinds. In 1923 he publishedDoomsland, which is viewed by many as his most significant literary contribution.

His wife Marjorie died in 1951, after which he married Iris, daughter of Charles Miskin Laing. Sir Shane Leslie died on August 14, 1971, at his home in Hove. He was survived by his wife and children, John Norman, Desmond, and Anita (Leslie) King. John Norman succeeded to the baronetcy, and Anita would follow in her father's footsteps and become an accomplished writer and biographer. "Leslie, Sir John Randolph ('Shane')". Dictionary of National Biography 1971-1980. Oxford/[Oxfordshire] ; New York: Oxford University Press, 1986. "Leslie, Sir Shane". The Dictionary of Irish Literature edited by Robert Hogan (Westport, CT: Greenwood Press, 1996): p.706