Although he was a younger son Adam Mytton inherited his family’s original home in Shrewsbury. He followed its traditional path to local eminence: during 1518-19 he joined the drapers’ company, whose control of the Shropshire cloth trade was beginning to be contested by the mercers’ guild, and not long afterwards undertook his first municipal office.
Once Mytton had established himself in the company and in local administration, his Membership of Parliament was the next obvious step in his progress: in this too he was following family precedent, which was already long established when in 1437 his great-grandfather William Burley had been chosen Speaker. Mytton’s election in 1523 almost certainly represented a victory for the drapers, for he and his partner Edmund Cole were both of that company. He was presumably the drapers’ nominee in the two following Parliaments (and again in 1542), but on both these occasions he sat with a mercer of noble origin, Robert Dudley aliasSutton. Although these two men represented opposing factions, no ill feeling is known to have existed between them: when they were returned in 1529 they may have been already related by marriage, and during the 1530s they were to be associated in local issues. Mytton did not sit for Shrewsbury in the Parliament of 1539, but three years later he made his fourth and final appearance in the House, sitting this time with his nephew Richard Mytton. No details have come to light of his part in the proceedings of the Commons, but when he petitioned Cromwell in 1538 for some former monastic property in Shrewsbury he reminded the minister that for 16 or 17 years he had been ‘one of the insensyscyant [sic] of the number of the Common House at all times to my little power ready to prefer the King’s cause’, and that during the Parliament of 1536 he had been advised by Cromwell to spare no labour in soliciting anything in the King’s gift in Shropshire that he would like in reward.
In 1536 Mytton raised and commanded 100 men against the northern rebels. His exemplary loyalty and his association with Cromwell, whose ‘accepted’ servant he considered himself, qualified him for a higher status in local administration than he had hitherto enjoyed, and in 1538 he was named for the first time to the Shropshire bench. The fall of Cromwell did not harm him, and by 1543 he had been appointed to the council in the marches of Wales, of which he remained an active member until his death. This appointment brought with it a considerable extension of influence and later a knighthood: during the late 1540s and 1550s it also called for much journeying throughout the marches and in Wales. He made a second home for himself in Radnorshire but his absences from Shrewsbury did not diminish his prestige there: he acted as the council’s spokesman in the town, presumably arranging for John Evans to be elected to Parliament early in Edward VI’s reign, and ensured that the requirements of successive regimes were observed, as when during 1546-7 he supervised the burning of religious paintings. Although his own parliamentary career ended in 1544, he used his various offices to obtain seats in the Commons for kinsmen, friends and clients of the council. His alleged failure as sheriff to send the precept to New Radnor Boroughs for the election there in the autumn of 1553 gave rise to acrimony and to an action against him in the Exchequer by the attorney-general. Mytton answered the charge in Michaelmas term 1554, arguing that the case should be dismissed because statutes governing elections in England did not apply to Wales. The outcome is not known, but the affair seems to mark the beginning of a downward turn in his career: he was less in evidence in his last years, but old age or ill health may have been the reason.
At the beginning of Mary’s reign Mytton had sued out a pardon as of Shrewsbury and Presteigne, but he had given up his second house by 10 July 1561, when as a sick man he made his will. He left his wife all his property in Shrewsbury and its suburbs, and after remembering his servants he divided the remainder of the estate between his two daughters. He named his wife executrix, and his nephew Richard Mytton and his friend John Bradshaw I overseers: the will was proved on the following 4 Oct.