Powle was a member of the
Royal Society, and was probably abroad for part of the time before the Glorious Revolution. He gained the confidence of
William III, at that point the Prince of Orange, and on 16 December 1688 he and
Sir Robert Howard held a long and private interview with the prince at
Windsor. When William called together at St. James's a number of members of Charles II's parliaments and common councilmen, Powle attended at the head of 160 former members of the House of Commons. On their return to Westminster to consider the best method of calling a free parliament, he was chosen chairman. He bluntly asserted that "the wish of the prince is sufficient warrant for our assembling"; and on the following morning he read addresses to William, praying that he would assume the administration and call a convention. To the Convention parliament Powle was returned, with
Sir Christopher Wren, for
Windsor. He was voted to the Speaker's chair over the head of his old opponent, Sir Edward Seymour (22 January 1689). Powle's speech on the opening of the convention exercised influence on subsequent debates. As Speaker, he congratulated William and Mary on their coronation, 13 April 1689, and presented to William the
Bill of Rights on 16 December 1689. Powle was summoned, with seven other commoners, to William's first privy council. On the remodelling of the judicial bench, when
John Holt was appointed
justice of the king's bench and
Sir Robert Atkyns chief baron, Powle, on 13 March 1690, received the patent of
master of the rolls. While the convention sat, William relied on Powle's advice. Powle was returned for Cirencester for William's first parliament, which met on 20 March 1690, but was not re-elected Speaker and was unseated on petition. Powle then devoted himself to his duties as master of the rolls, and successfully claimed, in accordance with precedent, a writ of summons to attend parliament as an assistant to the House of Lords. He spoke in the upper house in favour of the
Abjuration Bill on 24 April 1690, but wished the oath imposed sparingly and only on office-holders. ==Death==