By the middle of the eighteenth century the Wynns of Glynllivon held the dominant interest in Caernarvonshire. At the general election of 1754 Sir John Wynn persisted in his determination to oppose the sitting Member, William Bodvell, despite pressure from the Duke of Newcastle; and to avoid a contest Lord Powis agreed to return Bodvell for Montgomery. When in 1761 Thomas Kyffin of Maenan canvassed Caernarvonshire, Sir John Wynn moved to the borough and left the county to his eldest son, Thomas. In 1768 Thomas Wynn resisted the challenge of William Wynne of Wern, but the position of the Glynllivon family was fast deteriorating. Sir John died in 1773; Thomas, according to John Robinson, ‘was personally disliked for some slights to the gentlemen’; and the attempt of one family to monopolize both Caernarvon county and boroughs was causing resentment. In 1773 Lord Bulkeley came of age and determined to restore his family’s traditional interest in the county, dormant since 1713. He thought of standing himself, but found that Thomas Assheton Smith had already declared his candidature. ‘Three candidates’, wrote Bulkeley to George Grenville, 9 Sept. 1774,1 ‘I plainly saw would certainly be of infinite service to Sir Thomas, and as I did not wish him well I immediately told Mr. Smith ... I did not hesitate a moment to give him every support in my power.’ Sir Watkin Williams Wynn, the bishop of Bangor, and most of the leading squires also supported Smith; and the hold of the Glynllivon family on the county seat was broken.

In 1780 Bulkeley supported John Parry; Smith, indignant, retired from the contest, unable to make much headway without Bulkeley’s support; and Thomas Wynn, now Lord Newborough, declined the poll after a canvass. In 1784 the Bulkeley interest again secured the return of John Parry, after a brief canvass by Lord Penrhyn.