He was admitted at Lincoln's Inn on 25 November 1755[1] and called to the bar in 1764.
In March 1763 he was appointed Receiver of the King’s revenues for Monmouthshire, Herefordshire and Gloucestershire.
[2] Lewis’s uncle Thomas Lewis, who had been MP for New Radnor for 46 years, wanted to return him as Member of Parliament for New Radnor but there were historical mistakes in the registration of freeman.
His first wife had died in 1774 and he married as his second wife Ann Frankland, daughter of Sir Thomas Frankland, 5th Baronet on 24 March 1778.
At Lewis's third parliamentary attempt in 1780 there was a double return and his opponent was successful.