Born on 25 August 1773 at Darnlaw, in the parish of Auchinleck, Ayrshire, he was third son of James M"Gavin, farmer, by Mary M"Millan, a farmer"s daughter of Muir-Kirk, in the same shire. The farm of Darnlaw belonged to James Boswell. In 1783 his father moved to Paisley.
During the three years that he remained there he studied English grammar and composition.
Almost entirely self-educated, McGavin in 1785 was bound apprentice to a weaver, but in 1790 he entered the service of John Neilson, then a Paisley printer and bookseller. About 1796 he set up a small thread business at Paisley, but was unsuccessful. In January 1799 he was engaged as bookkeeper to David Lamb, an American cotton merchant in Glasgow.
To whose two sons he also acted as tutor.
In April 1804 he was regularly ordained Ramsay"s co-pastor. He withdrew from the pastorate in 1807.
He then joined the congregation of Greville Ewing. He also became an itinerant preacher and a director of religious societies at Glasgow.
His own business proving unprofitable, McGavin took on in 1822 the Glasgow agency of the British Linen Bank.
He died on 23 August 1832. Monuments to his memory were erected in the Glasgow Necropolis, and at Auchinleck. On 7 October 1805 McGavin married Isabella Campbell of Paisley.
McGavin belonged to the Antiburgher Church communion, and was a member of the congregation of James Ramsay, whom he joined about 1800, and subsequently assisted to form an independent church, occasionally preaching for him.
