He often wrote under the pseudonym of Captain Thomas Newte and this fictitious character had his own history and received independent recognition.
Born in the parish of Forteviot, Perthshire, he was son of Matthew Thomson, builder, carpenter, and farmer, by his wife, who was the daughter of the schoolmaster of Avintully, near Dunkeld, with surname Miller.
Completing his theological studies at St. Andrews and Edinburgh, Thomson was ordained on 20 March 1776 assistant to James Porteous, the minister of Monivaird, Perthshire; but his habits and tastes clashed with the post.
He claimed to be a landowner in Devonshire and to own several ships run by the East India Company.
[5] Thomson made a reputation with his continuation of Robert Watson's History of Philip III of Spain, 1783, for which he wrote the fifth and sixth books.
During the rest of his life, he wrote pamphlets, memoirs, biographies, voyages, travels, and treatises.
[1] In politics, he defended the French Revolution in 1792 in an open letter to Samuel Parr; and as the columnist "Ignotus" in The Oracle he supported Charles James Fox.