Loch's date of birth is unknown, but he was probably born in Fife. His father, John Loch, was a merchant of Anstruther Easter who bought the estate of Over Carnbie in Fife. Loch died in Edinburgh on 14 February 1780. As a Young man he went to sea, and became master of a merchant ship before settling in Leith as a merchant and shipowner. In 1772 he is described as a ‘merchant of Edinburgh’. He also served as manager of the Edinburgh Whale Fishing Company, and fitted out two ships for whaling off Greenland. He married Anna Stewart, daughter of Dugald Stewart, Baron of Appin.
From The Biographical Dictionary of British Economists in Oxford Reference.