He was born c. 1667, the son of John Gillan.[1] After his education at Marischal College, Aberdeen, he worked as a bookseller.[1] He married Isabel Wingate, daughter of the Reverend John Wingate, Incumbent of Denny, and Margaret Marschall.[1] He published Vindication of the Fundamental Character of Presbytery (1713), Life of Bishop Sage (1714), and is reputed to be the author of Carnwath's Memoirs.[1][2]