Engineer and inventor. Born in Glasgow, Clerk studied at the Andersonian College, now part of the University of Strathclyde. He invented the two-stroke Clerk Cycle engine (1877), which was used for large gas and small petrol engines.
Clerk joined George Marks as a partner in the patent company of Marks & Clerk (1882), which is now a major international player in patents and intellectual property law.
An authority on internal combustion engines, he led engineering research during the First World War. Clerk was appointed director of engineering research for the British Admiralty (1916) and was knighted in 1917. He died in Surrey (England).