| Constituency | Dates |
|---|---|
| Bletchingley | 15 Jan. 1745 – 1761 |
| Great Marlow | 1761 – 3 July 1783 |
William Clayton generally followed the lead of his elder brother. He adhered to Newcastle, voted against the peace preliminaries, December 1762, and opposed the Grenville Administration. Rockingham in July 1765 classed him as ‘pro’ and in November 1766 as ‘Whig’, the same as his brother; like him, William Clayton did not vote on the land tax, 27 Feb. 1767, and on 2 Mar. was classed by Newcastle as ‘doubtful or absent’.
He had a considerable interest at Great Marlow, an expensive and corrupt constituency, where he stood contests in 1768, 1774, and 1780. After his brother’s death he supported the Grafton and North Administrations, and the only occasion on which he is known to have voted against the court was on Dunning’s motion, 6 Apr. 1780. Only a few speeches by him are recorded: 21 Feb. 1771, on the Reading canal bill; 27 Mar. 1771, in the debate arising from the attack on North by a mob; 22 Apr. 1771, on the game bill; and three times in May 1780 when he moved for strangers to withdraw. The English Chronicle wrote in 1780 that he was ‘not distinguished for any powers of oratory, or superiority of intellectual attainments’. On 18 Feb. 1783 he voted for Shelburne’s peace preliminaries, and died 3 July 1783.