His grandfather and namesake, James Keith (17 April 1825 – 21 March 1901) and his father, Sir Henry Shanks Keith (26 Dec. 1852 – 9 July 1944) both served as Provosts of Hamilton, Lanarkshire, Scotland; his father also being appointed a Deputy Lieutenant and Honorary Sheriff of Lanarkshire.

His family owned the large high-end grocery business, Keith's of Hamilton, operating from substantial premises on the town's Cadzow Street (the building remains.)

During World War I, he joined the Seaforth Highlanders, and was wounded in France.

In 1953, he was made a Lord of Appeal in Ordinary, and was created a life peer, as Baron Keith of Avonholm, of Saint Bernard's in the City of Edinburgh.

On 7 July 1915 James Keith married Jean Maitland Bennett.