Molesworth’s father had been in great favour with Cromwell, who granted him Irish estates. Molesworth himself had been an active supporter of William III in 1689. Noted for his skill as a political pamphleteer and the vigour of his speeches in debates, he was returned for Mitchell in 1715, having been appointed a lord of Trade for his ‘small share of the King’s accession to the Crown’, but he resigned that office in favour of his eldest son, John, at the end of the year.
Molesworth became one of the fiercest critics of the Administration on the collapse of the South Sea bubble, in which he had lost £2,000 of borrowed money. In December 1720 he insisted that the South Sea directors should be called to account, and a month later he declared that, like Roman parricides, they should be sewn up in sacks and thrown into the river. Elected a member of the secret committee set up by the Commons to inquire into the scheme, he became ‘the favourite of the afflicted’, who sought redress through his means. Having urged that the Government should take steps to secure the person and papers of Knight, the South Sea Company cashier, he later denounced as a frivolous pretext their offer to place before the House an exchange of letters with the Emperor, showing it was impossible because of the special privileges of Brabant, where Knight had taken refuge. But he absented himself from the division on Charles Stanhope on 28 Feb. after receiving a message from the King asking him as a personal favour not to vote in that division. On 25 May 1721 he spoke unsuccessfully in favour of allowing Sir John Blunt £10,000, since Blunt had provided the committee with more information than any other director, and on 1 June he carried a proposal allowing the like sum to Sir Robert Chaplin.
On 19 May 1721 Molesworth wrote to his eldest son
I continue steadfast in my purpose, notwithstanding the opposition given by the Court, old and new ministry, the majority of the Parliament (who are dipped) and the relations, bribed and interested, of all concerned ... Every day opens fresh scenes of misery and robbery ... The gentlemen at the helm were not only content to plunder, but connived at all that did so. The land tax which is the clearest of all the branches of the revenue, has had the collecting of it put into such hands, that the proper officers upon our requiring have made a return of about £690,000 in arrear for the last year 1720. This proceeds from appointing collectors such as were their friends, relations (staunch Whigs all), beggars themselves, their securities little better, who run away with the public money, or have laid it out in purchasing South Sea stock for themselves, the Treasury not calling them to account in time ... all the methods and course of the Exchequer being broken.
HMC Var. viii. 312-13.
He was not, as was generally supposed, the author of the attacks on the Sunderland government printed in Cato’s Letters, which were written by John Trenchard. His last recorded speech, attacking the treaty with Sweden, 19 June 1721, was ‘very much warmer ... than any of the Tories’ and was said to have been particularly resented by Carteret.
At the general election of 1722, Molesworth agreed to stand as an opposition candidate for Westminster, but withdrew before the poll.