John Cochrane was born in 1750, the second living son of Thomas Cochrane and Jane Stuart. His father was serving as a Commissioner of the Excise for Scotland at the time, but unexpectedly inherited the title of Earl of Dundonald in 1758 on the death of his younger cousin William, the 7th Earl.
From 1779 to 1783 Cochrane acted as a deputy paymaster in British North America. In May of 1783 Cochrane was sued by General Haldimand for refusing to sue merchants himself for amounts owed the Crown for bills of exchange. Cochrane and the merchants lost in the provincial courts, a painful loss which demonstrated to the merchants the need for a better legal system in Quebec.
From 1790 to 1792 Cochrane held the contract for victualling the British fleet in India.
In 1793 Cochrane was appointed as Deputy Commissary for North Britain.
