John born c.1280, first Lord Charlton of Powys came of a family of minor Shropshire landowners, with property in Charlton near Wellington.  John is recorded as serving in Scotland, as the constable of fifty-nine Staffordshire archers. By June 1305 he had entered the service of the prince of Wales, and when Prince Edward became king, Charlton remained in the royal household. Recorded as a king's yeoman on 18th September 1307, he was styled knight shortly afterwards. In January 1308 he accompanied the king to France for his wedding, and in 1309 served in Ireland. In March of that year he was granted the Shropshire manor of Pontesbury, but on 25th June greater prospects opened up with the death of Gruffudd ab Owain, lord of Powys. on 26th July 1309, Charlton  married Gruffudd's sister and possible heir, Hawise de la Pole, on that day receiving livery of the castle of Welshpool and the rest of Gruffudd's lands. Hawise was the daughter of Owain ap Gruffud and Joan Corbet

John and Hawise has two sons

John Cherleton

Lewis Cherleton, Bishop of Hereford.

In 1310 Charlton raised 400 men for an abortive Scottish campaign. Either in that year or in 1311 he became the king's Chamberlain. The lords ordainer demanded his removal from office and the court, and when the demand was ignored, repeated it. But Charlton retained his place, and in 1313 accompanied the king and queen to France. It was probably his royalism that had aroused the antagonism of the ordainers, but in 1311 he also became involved in one of the most important of the private disputes which, by drawing in the king and his adversaries on opposing sides, did so much to undermine public order in the reign of Edward II. Charlton, an aggressive and acquisitive man, quarrelled with his wife's paternal uncle, Gruffudd de la Pole (that is, Gruffudd of Welshpool), over the latter's minor lordships of Dinas and Mechain Is-coed. Gruffudd responded in October 1311 by challenging Charlton for the whole lordship of Powys, claiming his elder brother's lands on the grounds that under Welsh law there was no succession through females; Charlton's claim, by contrast, was based on English inheritance practice. Gruffudd resorted to force as well as to law, raising a large Welsh force which besieged Charlton and his wife—whose exertions earned her the sobriquet of Gadarn (‘the Hardy’) among the Welsh—in Welshpool Castle. Only in September 1312 was the siege raised, through the efforts of Roger (V) Mortimer of Wigmore. The fact that Gruffudd then turned for help to Thomas of Lancaster, becoming a retainer of the earl, while Charlton could count on the king's support, can only have helped to keep the dispute simmering, in spite of a grant of pardons to both principals in November 1313.

On 26th July 1313 Charlton received a personal summons to parliament, and has consequently been regarded as having become Lord Charlton, although it would probably be more accurate to say that he had been acknowledged as Lord of Powys in the right of his wife. On 25th January 1314 he was granted the custody of Builth Castle, thereby extending his influence far into the south-west. Later that year he led a force of 2263 Welsh foot soldiers on the Bannockburn campaign. In May 1315 the men of Builth complained of Charlton's oppressions and extortions, but he remained in favour with the king, who in February 1316 ordered him to act against rebels in Glamorgan. In July he was also engaged in reducing Bristol to order. In the meantime Gruffudd de la Pole had reopened his claim to the lordship of Powys. The parties were summoned to appear before the king, but Gruffudd failed to attend, leaving Charlton free to make allegations of his opponent's violent ways. Gruffudd received a pardon in October, but the grant to Charlton in 1317 of the custody of parts of Edgmond, Ford, and Newport in Shropshire only strengthened his position in the Welsh marches, and though in October 1318 the king confirmed Gruffudd in his rights in Dinas, his opponent lost little thereby, and enfeoffed members of his own family with lands in Powys.

In 1318 Charlton ceased to be the king's Chamberlain. He was replaced by the younger Hugh Despenser, whose territorial ambitions in Wales and its marches in subsequent years seem to have done more than anything else to undermine Charlton's hitherto firm loyalty to the king. In 1321 he was ordered in vain to keep the peace in his lordships, and he also quarrelled with the king over the advowson of Welshpool church. On 29th November he attended the meeting of the ‘good peers’, whom Thomas of Lancaster had summoned to Doncaster, and appears to have taken arms against the king, though he was captured early in 1322, probably in Welshpool Castle, before he could join the baronial army. But he did not suffer as many of Edward II's enemies did following Lancaster's defeat. Indeed, he was serving the king against the Scots within a week of the battle of Boroughbridge, and on 11th September he received a formal pardon. He may have been saved by memories of past services, or perhaps his Welsh lands, which were then in considerable disorder, were deemed uncontrollable without him. But Charlton was not truly reconciled with a government in which Despenser was now supreme. He remained in touch with the regime's greatest enemy, his former ally Roger Mortimer (whose daughter was married to Charlton's son), and when Mortimer and Queen Isabella invaded England in the autumn of 1326, he gave them material assistance by arresting and executing the earl of Arundel, a partisan of the king who was also a patron of Gruffudd de la Pole.

Charlton now turned on Gruffudd, expelling him from his lands and causing damage estimated at £4000. Efforts to restore order had little effect, and in November 1330 Charlton and Gruffudd were said to be gathering soldiers. By May 1332 Gruffudd had died, but his heir, his wife's brother Thomas ap Rhodri (the father of Owain Lawgoch), appears to have maintained the dispute with Charlton, who also fell out with Richard (II) Fitzalan, the new earl of Arundel. Perhaps it was to ease the tension in the marches that on 29th June 1337 Charlton was appointed Justiciar of Ireland. With him went his wife and children, his brother Thomas, who had been appointed chancellor, 1000 marks in cash, and 200 Welsh foot soldiers. But John Charlton quarrelled with his brother, perhaps over the money provided for them by the English exchequer, and in the following June he returned to England. A brief dispute with Thomas ap Rhodri over the lordship of Dinas in 1339 showed that Charlton had not lost his ability to maintain a feud, but old age eventually told upon him. In 1346 he was reported to be old and ill, but none the less he lived for another seven years, dying in 1353. He was buried alongside his wife, who had predeceased him, in the church of the Greyfriars in Shrewsbury. Fourteenth-century stained glass, now in St Mary's, Shrewsbury, but originally in the Greyfriars, shows a knight bearing the arms of Powys who is probably Charlton.

In his latter years the elder John Charlton showed himself concerned at various times for the well-being of his family, his lands, and his soul. In 1343 he arranged for the marriage of his grandson, John Charlton, to the daughter of Ralph Stafford, first earl of Stafford. His incorporation of the town of Llanidloes in 1344 recalls licences for markets at Welshpool and Machynlleth which he had earlier gained from the crown. In 1336 he obtained a papal faculty for a portable altar, and in 1341 a licence for the celebration of divine worship at Charlton, and he showed zeal for the reformation of the corrupt Cistercians of Strata Marcella (Ystrad Marchell) in eastern Powys. Yet in his relations with the church, as in his dispute with Gruffudd de la Pole, Charlton also showed the violence and arrogance which, along with administrative and military ability, had marked his whole career. Some time between 1309 and 1318 the Cistercians of the abbey of Cwm-hir complained of oppression by Charlton at Arwystli in Powys, and in his dealings with Strata Marcella he was even more abrasively high-handed; in 1333 it was alleged that he was refusing to allow the abbot of Clairvaux's commissary to enter his lands, having proclaimed that ‘I am Pope; I am King, and Bishop and Abbot in my land’ (Rees, 411). However, Mercer's research into architectural activity by Charlton and his kinsmen shows their readiness to benefit from the more peaceful life now available near the border.