Son of Vincent Maynon of Invault and Agnes Bouvard Fourqueux, in 1758 he married his cousin Elizabeth Adelaide Bouvard Fourqueux.
He was advisor to the Investigations of the Parliament of Paris in 1741. He was then master of requests (4 March 1747 - 29 January 1766), president of the Grand Council (1753), steward of Picardy in Amiens (August 1754). Appointed State supernumerary on 5 October 1766, he became Counselor of State on 7 November 1767.
He was appointed Comptroller General of Finance on 22 September 1768 and Minister of State on 10 December 1768.
He used the ordinary expedients, while preparing drastic measures that should be discussed on 19 December 1769. The Boards of Finance gathered together, in a committee comprising members of both Councils. Following this meeting, Louis XV decided not to submit the measures envisaged in the expanded Council, which led to his resignation on 19 December 1769.
Clément Charles François de Laverdy
| Controllers-General of Finances
22 September 1768 – 19 December 1769
Joseph Marie Terray