O'Brien, Sir Edward (1705–65), 2nd baronet, MP, and racehorse owner, was born 7 April 1705, elder son among three children of Lucius O'Brien and his wife Catherine Keightley, daughter of Lady Frances Hyde, a sister-in-law of King James II (qv). His brother Thomas and sister Ann both died young and unmarried. His paternal grandfather, Sir Donough O'Brien, MP, was reputedly the richest commoner in Ireland. Lucius predeceased Donough by a few months, so Edward inherited the family estate of Dromoland, Co. Clare, in 1717. His education commenced in 1714; he was the first of his family to attend Oxford University, matriculating at Balliol College (October 1721).
Edward, like his father and grandfather, developed an early interest in expensive pastimes, especially field and equestrian sports. Point-to-point racing and steeplechasing benefited from both his attention and his income; his passion for field sports was probably spurred by his residence, until his father's death (1717), at his mother's mansion, Castlemartin, Co. Kildare, adjacent to the Curragh. When in residence at Dromoland he devoted most of his attention to his stud farm at nearby Ardsollus. He was a regular visitor to Newmarket, Suffolk, around mid century and became one of the principal racehorse owners in Ireland. In the two decades after 1735 he imported prime bloodstock into Ireland, principally ‘Dairymaid’, and produced the first Irish equine pedigrees.
His lawyer and agent repeatedly criticised his inability from the 1730s onwards to live within his annual income of £4,000. As an MP for Co. Clare (1728–60, 1761–5), O'Brien maintained a residence in Dublin, as well as on George St., Hanover Square, London, which he sold before 1732; he had been elected as a tory to represent Peterborough at Westminster (1727–9 April 1728). His only link to Northamptonshire (in which the borough then lay) was through his kinsman Henry O'Brien (d. 1741), 8th earl of Thomond, who held estates in the county. After being unseated on a petition concerning the validity of the poll, he never again stood for election in Britain.
His eldest son, Lucius O'Brien (qv) (1731–95), joined him in parliament in 1761 as MP for the borough of Ennis (1761–95). The elder O'Brien was generally a poor attender, especially early in his political career; in 1733 he was ordered into custody by the commons for non-attendance. He intensely disliked party divisions and factional rivalries; in 1749 he resolved to quit College Green and politics, against the acrimonious background of the lord lieutenancy of the earl of Harrington (qv), which saw considerable conflict over the election of Charles Lucas (qv) as well as the unprecedented revenue surplus of that year; he complained that ‘there is so much villainy in Dublin . . . where all confidence between man and man, and all publick [sic] faith, is brought to an end . . .’ (Inchiquin manuscripts, no. 538).
In 1741 he was elected provost of the borough of Ennis, and still held that office in 1761, although it is not clear whether he had done so continuously. He was also commissioned a colonel in the Clare Dragoons, though not untypically the force was to remain largely insignificant; a return made to the lord lieutenant in 1756 listed twenty-four officers and 134 rank and file. In 1764 he served as an commissioner of the navigation board of Limerick.
In mid-century he produced detailed drawings of a proposed grand residence for Dromoland, but they were unfulfilled. However, he did construct a two-storey octagonal gazebo on Turret Hill opposite the entrance to Dromoland Castle, which still survives, providing a fine vantage point from which to both supervise the training of his horses and enjoy the point-to-point races that ran on the course he had laid out below. He also built an elegant stable block at Dromoland in 1736. Such accomplishments increased the weight of his spiralling debt, forcing him to place Ardsollus on the market in 1742. Indeed, the extent of his desire for fine living was evidenced by his ability to bypass Limerick's merchant community and directly source his own supplies of claret, burgundy, and champagne from France. With Lucius repeatedly urging the need for economy to his father, especially after 1758, O'Brien retorted on one occasion that ‘my sole amusement is my horses, and . . . I neither play cards or dice, keep neither whores nor hounds’ (McNamara, 70). The following year a trust was established by his sons Lucius and Donough to manage the estate's debts.
He married (1726) Mary, daughter of Hugh and Ann Hickman of Fenloe, Co. Clare; they had three sons and five daughters. Mary died 20 February 1760, and Edward on 26 November 1765. He was buried in the family vault in Kilnasoolough (Kilnasoolagh) church alongside his grandfather, to whom he had earlier erected a monument there. A portrait of O'Brien is reproduced in Donough O'Brien, History of the O'Briens from Brian Boroimhe, AD 1000 to AD 1945–1949, 217.