Inventor. Sinclair was born in Wick (Caithness) and joined the telegraph department of the North British Railway in 1872 and was sent to Japan as inspector of telegraphs for the Japanese Government (1875-79). He returned to Scotland to work for the Dundee and Arbroath Joint Railway, but it was while an engineer with the National Telephone Company, based in Glasgow, he patented the first automatic telephone switchboard. Although not nearly as sophisticated as the system invented in 1891 by Almon B. Stowger in Kansas City (USA), Sinclair's system was being used in Coatbridge in 1886.
By 1911, Sinclair had risen to become Engineer-in-Chief of the National Telephone Company, shortly before it was taken over by the Post Office. He left to become General Manager of the British Insulated and Helsby Cable Company, but quickly helped his new employer to launch a new venture - the Automatic Telephone Manufacturing Company - of which Sinclair became managing director in 1912.
He was buried in Wick. One of Sinclair's original systems survives in the Royal Museum of Scotland in Edinburgh.
