Soon after the Restoration he returned to England, and had a favourable reception at the court of Charles II. An act of parliament restoring to him all the honours, castles, lordships, lands, &c., whereof his great-grandfather, grandfather, or father was in possession on 23 Oct. 1641, was read a first time in the English House of Lords on 18 Aug. 1660, and received the royal assent on 29 Dec. following (Historical MSS. Commission, 7th Rep. 127; Lords' Journals, xi. 133, &c.) By virtue of this statute he became seised of several estates in the counties of Meath, Westmeath, King's, Mayo, Galway, Sligo, Roscommon, and Tipperary. Captain Valentine Jowles, writing to the navy commissioners, 26 June 1661, states that the lords justices of Ireland had sent him to Chester to fetch the Earl of Roscommon, whom they much needed at their councils (Cal. of State Papers, Dom. Car. II, 1661–2, p. 18). He took his seat in the Irish parliament by proxy on 10 July 1661, and on 16 Oct. following he had a grant of the first troop of horse that should become vacant, pursuant to privy seal dated 23 Sept. preceding. In 1661 he addressed to the king a petition in which he says that his father and grandfather being protestants, and having from the beginning of the rebellion constantly adhered to the royal cause, lost at least 50,000l. or 60,000l. for their loyalty to Charles I. His father, he adds, died about 1648, leaving him dependent upon the charity of his friends, and in conclusion he asks for part of the money which the king had to receive from the adventurers and soldiers of Ireland (Egerton MS. 2549, f. 120). By the interest of the Duke of York he became captain of the band of gentlemen pensioners. In April 1662 he married Lady Frances Boyle, eldest daughter of Richard, earl of Burlington and Cork, and widow of Colonel Francis Courtenay.
Shortly after his return to England at the Restoration he made friends who led him into gambling. His gaming led to duels, though he used to say that he was more fearful of killing others than of losing his own life.
At length, having a dispute with the lord privy seal about part of his estate, he found it necessary to return to Ireland, and soon after his arrival in Dublin the Duke of Ormonde made him a captain in the guards. During his residence in Ireland Roscommon had many disputes, both in council and parliament, with the lord privy seal, then lord-lieutenant, who was considered one of the best speakers in that kingdom. The earl was generally victorious, and the Marquis of Halifax said ‘that he was one of the best orators, and most capable of business too, if he would attend to it, in the three kingdoms.’
Having settled his affairs in Ireland he returned to London, and received the appointment of master of the horse to the Duchess of York. He now attempted the formation of a literary academy, in imitation of that at Caen. The members of this little body included the Marquis of Halifax (who undertook the translation of Tacitus), Lord Maitland (who here began his translation of Virgil), and Roscommon himself (who wrote his ‘Essay on Translated Verse’). The Earl of Dorset, Lord Cavendish, Colonel Finch, Sir Charles Scarborough, Dryden, and others occasionally joined the meetings of the academy. On the occasion of the visit of the Duchess of York to Cambridge (28 Sept. 1680), Roscommon had the honorary degree of LL.D. conferred upon him. On 22 May 1683 he received the degree of D.C.L. from the university of Oxford.
Dr. Johnson, following Fenton, relates that after the accession of James II the earl resolved to retire to Rome on account of the religious contentions which then took place, telling his friends that ‘it would be best to sit next to the chimney when the chamber smoked.’ The date of the earl's death, which took place at his house near St. James's in January 1684–5, about three weeks before the death of Charles II, proves the incorrectness of this statement. Luttrell notes on 16 Jan. 1684–5 that ‘the Earl of Roscommon was lately dead.’ A few days before his death he requested a friend—a clergyman—perhaps Dr. Knightly Chetwood [q. v.], to preach a sermon to him at St. James's Chapel. He went in spite of warnings, saying that, like Charles V, he would hear his own funeral oration. Returning home he remarked to the preacher that he had not left one paper to perpetuate the memory of their friendship. He thereupon wrote what Dr. Chetwood calls ‘an excellent divine poem,’ which, however, the physicians would not allow him to finish. The fragments of this poem were delivered by Chetwood to Queen Mary. A few stanzas have been printed (Gent. Mag. new ser. xliv. 604). Just before he expired the earl pronounced with intense fervour two lines of his own version of the ‘Dies Iræ:’
Do not forsake me at my end.
He was buried with great pomp in Westminster Abbey, ‘neare ye Shrine staires,’ on 21 Jan. 1684–5 (Chester, Westminster Abbey Registers, private edit. 1876, p. 212; Collect. Topogr. et Geneal. viii. 6). There were about
