John Myddelton succeeded his brother as a Tory at Denbigh Boroughs in 1733, concluding an agreement with Watkin Williams Wynn, under which they undertook to support one another in Denbighshire at the impending general election. Re-elected without a contest, he voted with the Opposition on the convention in 1739 and the place bill of 1740, although early in 1739, with a view to recovering the county seat, he had formed an electoral alliance with the Government as a result of which his kinsman, William Myddelton of Gwaynynog, was appointed receiver general of revenue in North Wales. Standing for the county seat against Wynn in 1741, he was heavily defeated at the poll but was returned by William Myddelton, who had been appointed sheriff of Denbighshire in the previous year. At the opening of the new Parliament he voted with the Government on the chairman of the elections committee. After Walpole’s fall he was unseated by the House of Commons, who committed William Myddelton to Newgate, also having him turned out of his receivership and the commission of the peace.1NLW Chirk Castle mss E. 3201, 4650, 4795, 5795, 5296, 5423; CJ, xxiv. 18-19, 89-92.
John Myddelton died 9 Apr. 1747.