Following the establishment of Beaumaris the inhabitants of the nearby township of Llanfaes were resettled at the village of Rhosfair in the south of Anglesey, renamed Llanfaes Newborough or simply Newborough. The charter of 1303 was confirmed and amplified throughout the middle ages. By the 16th century the town was governed by a mayor assisted by two bailiffs. Situated more conveniently than Beaumaris for administrative purposes and within four miles of the centre of government for North Wales at Caernarvon, it was made the shire town by Henry VII. Despite its position Newborough was not a suitable choice, being poor and lacking a gaol and other accommodation. No attempt seems to have been made at the Union to demote it in favour of Beaumaris, but a private Act to that effect (2 and 3 Edward VI, no. 54) was passed early in 1549. As shire town of Anglesey until that year Newborough returned Members to the Parliaments summoned during the 1540s.2

Indentures written in Latin survive for the Parliaments of 1542 and 1547. The earlier is in very poor condition yet legible enough to yield the contracting parties as the sheriff of Anglesey and the burgesses of Newborough. In October 1547 the sheriff seems to have had no hand in the matter, the bailiffs being the first party and more than 60 named electors living in the town being the other. In 1545 the sheriff included Newborough on the schedule for the island but two years later he sent in a separate schedule for the town. Both Members were local men, Owen ap Hugh having connexions with the knight for the island in the same Parliament and John ap Robert Lloyd holding a minor post in the Household. Lloyd was presumably responsible for the proviso quitting the town of payment to future Members for Beaumaris while assuring it of a say in their election, which was added to the bill making Beaumaris the shire town during its passage through Parliament.3