Comyn was the second son of Charles Comyn an English civil servant and was born at Shepherd"s Bush, London. His father in law William Emil Gerber of Sacramento, California was a merchant and financier, and may have supported his enterprises.
He was educated at Merchant Taylor"s School, and Dulwich College and subsequently founded his own shipping company - Comyn Singleton and Dunn of Gracechurch Street London EC1.
His great-uncle Stephen George Comyn had been naval chaplain to the English Admiral Lord Nelson. Through this business he went to California where he settled and became a businessman in San Francisco. During World War I Leslie Comyn, tried to persuade the United States Shipping Board (USSB) that they should build concrete ships.
They were not convinced so in 1917, he founded the San Francisco Shipbuilding Company at Oakland, California.
In January 1918 he started, on speculation, to build the first ship, called appropriately "FAITH" designed by Alan MacDonald and Victor Poss. The ship was an 8000 ton freighter, and, at the time, the largest concrete vessel with a sea-going capability in the world.
The ship was launched successfully in March 1918. Following this, on April 12, 1918, President Woodrow Wilson approved the Emergency Fleet Corporation program which oversaw the construction of 24 ferrocement ships for the war.
In May 1918, Faith left San Francisco on her maiden voyage, with 4300 tons of salt and copper ore, bound for Vancouver, followed by other voyages to Honolulu, Balboa, Callao, Valparaiso and New New York
In 1919 Comyn"s shipbuilding company sold the ship to the French-American Steamship Lincolnshire. The company is widely quoted in shipping law from the case "Dampskibsselskabet Dannebrog V. Signal Oil & Gas Company of, 310 United States. 268 (1940)". The question concerned is whether the Standard Oil were entitled to maritime liens for fuel oil delivered to Dannebrog"s vessels.
Dannebrog had chartered two ships - the "Stjerneborg" and the "Brand" - to West. L. Comyn & Sons in May 1933.
Standard Oil had previously modified a contract with Anglo Canadian Shipping to include the fuel oil requirements of vessels owned, chartered or operated by West. L. Comyn & Sons. Comyn married Ann Gerber, daughter of William Gerber, and had three children.
