Career
Born in Cambewarra, New South Wales, he received a primary education, and moved to Queensland in 1890, where he was a dairy farmer. He managed a company called Queensland Framers Company-operative. After the "fusion" of 1909, Sinclair, together with the rest of the Anti-Socialists, merged with the Protectionist Party to form the Commonwealth Liberal Party.
In 1917, the Liberal Party absorbed various Labor defectors (including Prime Minister Billy Hughes) and became the Nationalist Party.
Sinclair held Moreton until his retirement in 1919, after which he was appointed Chairman of the Queensland Butter Board. He died in 1926.