James was the son of James Oscar Max Clark and his wife Winifred Mary Halsall.

The Clark family lived at Tower Rais, Darnley Road, Barrhead, Glasgow from the early 1880s until the early 1920s. In 1929, J.O.M. Clark became Chairman of the "family" business of J&P Coats of Glasgow. He made regular visits to the United States to the Newark plant of their subsidiary company, The Clark Thread Company.  James accompanied him on several occasions. At the time of James’s death, his parents were living at 52 Clevedon Road, Glasgow.

James was educated at Harrow from 1928 and matriculated in 1933. He was up at Christ Church from 1933 until 1936.

He was a Cadet with the 165th Officer Cadet Training Unit and was gazetted to be a Second Lieutenant in the Coldstream Guards on 13 January 1940.

He was a Major in the 3rd Btn. Coldstream Guards when he was killed on 4 December 1943.

He is buried in the Cassino War Cemetery Plot VII. D. 11.

He is commemorated in the Royal Memorial Chapel, Sandhurst.

James Oscar Max Clark & Evan Baillie Noel wrote,
A History of Tennis. London: Oxford University Press for Humphrey Milford, 1924. 2 volumes, 4to., coloured frontispiece in vol. I, plates and illustrations, folding table at end of vol. II, original blue cloth gilt (spines faded). [Sold at Christies in 2005.]

LIMITED TO 800 COPIES. The archive of Oxford University Press reveals that by 1932 some 380 sets of this cloth-bound edition were pulped. The true limitation is therefore nearer to 420.