One of the two members of the House of Keys sent to Britain over the sale of the Island in 1765.

The Keys resolved that Thomas Moore and Hugh Cosnahan, gentlemen and members of their House, be their commissioners in the name and on behalf of the people of the Isle, to take such steps as they were advised to support and maintain the constitution, rights and privileges of the Island by application to the ministry or parliament of Great Britain. The two of them presented the petition of the House of Keys to the Commons, on behalf of themselves and the rest of the Keys as representatives of the people. The petition was afterwards used before the Commissioners of Inquiry to prove the delegation itself, and to prove that no meeting of the Keys was called by the Governor until 19 March, close on a month after the transaction of the sale had been closed.

A Thomas Moore, Deemster of the Isle of Man, was examined by the same Commissioners at Douglas on 26 and 27 September and on 5 and 7 October 1791, on the constitution and on the Lord's game. A Thomas Moore also signed the report on the Isle of Man Bill addressed to Lieutenant-Governor Richard Dawson on 27 April 1780, alongside John Quayle and Wadsworth Busk.