Barnewall, Sir Patrick (d. 1552), lawyer and MP, was the eldest son of Roger Barnewall of Fieldstown or Fedleston, parish of Clonmethan, north Co. Dublin, and his wife, Alison, daughter of Christopher Barnewall, 2nd Baron Trimleston. After entering Gray's Inn in 1527 he became a pleader in the Irish courts. He was agent for the Irish estates of Sir Thomas Boleyn, handled the affairs of several Irish monasteries and, with his uncle John Barnewall (qv) (later lord chancellor), was steward of seven estates in north Co. Dublin held by the English abbey of Kentsham.
Considered by Thomas Cromwell to be a reformer, Patrick Barnewall was appointed in 1534 king's serjeant-at-law and solicitor general. But, as a member of the Irish parliament of 1536–7, he led opposition to the suppression of religious houses, seeing it as a threat to his income not only as a lawyer and agent but as a lessee of monastic property and grantee of annuities secured on the revenues of monastic houses (many of which in the Pale were wealthy beyond the needs of their small communities). In the autumn of 1537 he was persuaded by the Irish council to go as a delegate to Henry VIII, a mission that put him in high esteem with Thomas Cromwell and proved crucial to his career and to the financial interests of all Palesmen. Once these interests were safeguarded, the suppression was carried. Barnewall was an agent to the commissioners appointed in April 1539 to give effect to the act. He himself benefited greatly by obtaining leases or grants of the priory of the Arroasian (Augustinian) canonesses regular nearby at Grace Dieu in the parish of Lusk (July 1541), the Carmelite house at Knocktopher, Co. Kilkenny (1542), and some of the possessions of St Patrick's cathedral, Dublin (1547).
In May 1538 Barnewall proposed the establishment in Dublin of a ‘house of chaunsery’ (inn of court). In 1541 former Dominican property in Dublin called Blackfriars was leased to twenty-one lawyers (of whom Barnewall was one) and was turned into an inn of court known as the King's Inns. From 1550 until his death Barnewall was master of the rolls. As such he assisted the lord chancellor, Sir Thomas Cusack (qv), in re-establishing order in Connacht; he later heard cases in Munster. It was said that he was proficient in Irish. He was knighted in 1552 and died in the same year. Patrick Barnewall married Anne, sister of Sir Thomas Luttrell (qv) (d. 1554), chief justice of the common pleas, under whose influence he is said to have been; they had a son, Christopher Barnewall (qv).