Eliot oratorical temperament, and as soon as he distrusted Buckingham he believed him capable of the worst crimes. He could not conceive him as he really was, incapable and vain, yet animated with a sincere desire to serve his country in displaying his own power. He set him down as a traitor who was prepared deliberately to sacrifice national interests in order to enrich and aggrandise himself and his kindred.
Eliot's conviction of Buckingham's misdemeanors was increased by the circumstances under which the parliament of 1626 opened. Charles, in order to rid himself of opposition, had kept at a distance from Westminster those among the members of the last parliament who had most severely criticised his policy by naming them sheriffs of their respective counties. It was therefore upon Eliot, who had been allowed to come to parliament, as having taken no part in that criticism, that the leadership of the new house fell. He began by calling for inquiry into the causes of the recent disaster, and when the committee which conducted the examination came upon traces of the misdeeds of the duke, he was inclined to exaggerate them, sometimes from mere want of knowledge of the circumstances under which Buckingham had acted. He soon came to the conclusion that the favourite, having dragged England into a war with Spain, was now about to drag her into a war with France, simply in order to fill his purse with the tenths of prize goods which were the perquisite of the lord high admiral. On 27 March he made a furious attack on Buckingham, and Charles, having intervened, persuaded the house on 4 April to present a remonstrance, asserting its right to question the highest subjects of the crown. It was a claim to render ministerial responsibility once more a reality, and thereby indirectly to make parliament supreme. He had already persuaded the house to vote a resolution granting subsidies, but to postpone the bringing in of the bill which alone could give legality to the resolution, and thus to dangle before the king's eyes the expectation of receiving supplies of war in order to induce him to abandon Buckingham.
As Charles was not to be persuaded, the impeachment of Buckingham, which had long been threatened, took its course. It was carried to the lords on 8 May by eight managers, of whom Eliot was one. It was on Eliot that devolved on 10 May the duty of summing up the charges, and in doing so he compared Buckingham to Seianus. On the 11th Eliot was sent to the tower, together with Sir Dudley Digges. The commons refused to proceed to business till their members were released. Digges was set free on the 16th, and Eliot on the 19th. They were the last members ever imprisoned for words spoken in parliament. As Charles could not stop the impeachment in any other way, he dissolved parliament on 15 June.
When the session was ended Eliot was dismissed from the justiceship of the peace and the vice-admiralty of Devon, and in 1627 was imprisoned in the Gatehouse for refusing to pay his share of the forced loan. He was liberated when it became evident that another parliament must be summoned, and when Charles's third parliament met, l7 March 1628, Eliot sat in it as member for the county of Cornwall. He at once joined in the cry against arbitrary taxation, and made his voice heard from time to time, though during the earlier part of the session the house was more inclined to follow Wentworth, who, though equally firm in his resolution to procure a removal of the subjects' grievances, was less incisive than Eliot in his mode of dealing with, the king. On 5 May Wentworth's leadership came to an end, upon Charles's refusal to concede his demands, and Eliot then came to the front, and joined Coke and the lawyers in promoting the Petition of Right, and in refusing to agree to anything short of its full acceptance by the king. When, after the king's first answer, that acceptance appeared unlikely, Eliot called upon the house to draw up a remonstrance, and, being interrupted by the speaker in a hostile allusion to Buckingham, refused to continue a speech in which he was not free to express all his mind. The king for once gave way, and on 7 June gave his assent to the Petition of Right. During the short remainder of the session Eliot continued the assault on Buckingham.
In the session of 1629, after Buckingham's murder, Eliot led the attack upon the Arminians and ceremonialists, who were, as he held, unprotestantising the doctrine and the services of the church. He pointed out that those who professed the opinions against which the House of Commons protested had been chosen for preferment in the church, and he proposed to meet the one-sided favour of the king by an equally one-sided proscription by parliament. He found, however, that it was easier to point out who were to be excluded from office in the church than it was to define the doctrines which were to be alone accepted. The house followed him in summoning to its bar some of the inculpated persons; but before they appeared on the scene a new question arose. The claim of the king to levy provisionally tonnage and poundage without consent of parliament was disputed, and while Pym wished to discuss the legal
