Welsh started his career in the Merchant Navy and from 1910 he was midshipman in the Royal Navy Reserve prior to the outbreak of the First World War, Welsh joined the Royal Naval Air Service in November 1914 as a pilot at RNAS Calshot.

[1] Welsh was shot down while flying a Sopwith Baby seaplane, landing only six miles northeast of Dunkirk on 23 April 1917, although he was unhurt in the crash.

14 Squadron, Welsh would serve on the Air Staff at Middle East Area headquarters from August 1921.

[1] Following his retirement, Welsh stayed in the United States and eventually divorced his wife, Dame Mary Welsh, to marry, in 1947, Elysabeth Cochran Carrere; formerly Mrs Barbour, who was previously married to United States Senator Warren Barbour.

[citation needed] Welsh would later become the North American representative for the Society of Motor Manufacturers and Traders until his death on 2 January 1962.