Clarke may be the ‘Thomas Clerk’ who was named with his brother-in-law, Maynard Colchester as one of the founding members of the Society of the Propagation of the Gospel in 1701.
He carried out charitable works in his neighbourhood among which he ‘built a gallery in the church, set up chimes in the steeple, put 90 poor children to school, gave bibles, catechisms etc., and distributed half-peck loaves and two oxen among the poor at Christmas’.
Soon after coming of age he stood for Parliament at Hertford at the 1705 general election on the Cowper interest.
After presenting an address from his borough congratulating the Queen on the Duke of Marlborough's victory, he was knighted on 24 July 1706.
He was a teller for committing the bill for restraining buildings on new foundations on 10 March 1709 and voted for the impeachment of Sacheverell in 1710.
He supported the Government, except on the civil list arrears in 1729 and on the later stages of the excise bill, having originally voted for it.