Miles de Stapleton was the eldest surviving son and, at his father's death, was already married to Sybil (also called Isabel), daughter and co-heiress to John De Bellew. Through her mother, Laderana, Sybil inherited a share of the possessions of the elder line of the Bruces, which were divided among four sisters and co-heiresses at the death of her uncle, Peter De Bruce of Skelton, in 1271. In memory of this connection with such a great house, Miles De Stapleton assumed the lion rampant of the Bruces as his arms. Miles served in the Gascon and Scottish Wars of King Edward I. In 1291, he was engaged on the King's business, under Roger De Mowbray, in Scotland. In 1295, he was in Gascony. In 1298, he was in the Falkirk Campaign, serving under his patron, Henry De Lacy, 3rd Earl of Lincoln. In 1300, he was summoned to the Siege of Carlaverock, but he was not mentioned in the famous French poem on the siege. In the same year, he accompanied the Earl of Lincoln on a mission to the Court of Rome, receiving, on 9th October, letters of protection for one year. Miles was entrusted by the King with the direction of the household of Edward, Prince of Wales. He served in the Siege of Stirling, in attendance on the Prince and, in October 1305, when the Earl of Lincoln wished to appoint Stapleton to manage his household during his absence at the Papal Court, the Prince informed the Earl that he had no power to give Stapleton leave to hold this post without the express command of the King. Stapleton was one of the experienced men of affairs to whom Edward I entrusted the difficult task of bringing up his son in businesslike and soldierly ways. Meanwhile, his estates and influence in Yorkshire were steadily increasing. The betrothal of his eldest son to a daughter of John of Brittany, Earl of Richmond, and a grand-niece of the King, and his second son's betrothal to one of the daughters of Brian FitzAlan, Lord of Bedale, connected him with two branches of the greatest family of his district, and increased the importance of the house. After the death of Edmund of Cornwall had led to the lapse of his vast property to the Crown, Edward I made Stapleton Seneschal of Knaresborough Castle and Steward and joint Constable of Knaresborough Forest. In 1305, he was, jointly with John De Byron, appointed commissioner to suppress the clubmen or trail?bastons of Lancashire, but they were shortly afterwards superseded.

With Edward II's accession, Stapleton's importance was, for the moment, increased. He became Steward to the King's Household and went abroad, in January 1308, on the occasion of the King's marriage at Boulogne. In a few months, however, he lost his stewardship and was forced to surrender the Royal Manor of Brustwick in Holderness, of which he had had custody, to Gaveston. In 1311, he was summoned to serve against the Scots. His losses, in the interests of the Gascon favourite, made Stapleton hostile to his old master, Edward, and attached him to Earl Thomas of Lancaster. He was, in October 1313, included, with his wife and three sons, in a long list of adherents of Lancaster who were then pardoned for the murder of Gaveston. Previous to this, however, he had received back the custody of Brustwick and, in the same year, he was thrice summoned as a Baron to Parliament. In 1314, he obeyed the summons to muster for the relief of Stirling. However, on 24th June, he was slain, along with two of his sons, at the Battle of Bannockburn.

By his first wife, Sybil, Stapleton left several children. The eldest, Nicholas, born in 1286, was also summoned to Parliament and died in 1343. His son and successor, Miles, died in 1372. Miles's only son, Thomas, died in 1373, whereupon the Barony fell into abeyance and the estates of the elder branch passed to his sister Elizabeth and remained with the Metham family, her husband's kin. A younger son of Miles and Sybil, Gilbert (died 1321), became Royal Escheator beyond Trent and, by his wife, Agnes, daughter of Brian FitzAlan, Lord of Bedale, was the father of Sir Miles (died 1364) and Brian De Stapleton (died 1394). After Sybil's death, Stapleton married, as his second wife, Joan (wrongly called Cecily), daughter of Peter De Tynedale, who survived him. By her, he had a daughter named Joan.