This firm was acquired by the Imperial Tobacco Company in 1930, of which company Sinclair was later chairman from 1947 to 1959 and president. He was also Chairman of the Finance Corporation for Industry and of the Bristol Waterworks Company.
Sinclair's business was acquired by Imperial Tobacco in 1930, a position Sinclair held until he became chairman from 1947 to 1959 and president. Furthermore, Sinclair served as chairman of the Finance Corporation for Industry and Bristol Waterworks Company.