On 14 November 1768 John Wilkes presented a petition through Mawbey. It covered points including the case brought over The North Briton, an allegation that Lord Mansfield had altered a record, and an allegation that Philip Carteret Webb had bribed Michael Curry, Wilkes's printer and a witness. Speeches by Mawbey on the proceedings against Wilkes were later published, in the Debates by Sir Henry Cavendish, 2nd Baronet. Mawbey was a significant force in the Bill of Rights Society that gave Wilkes practical support, and took Wilkes's side in the internal struggle, leading to a split in the Society, with supporters of John Horne.
