at Eton, he served for a time in the navy. In 1778 he assumed the additional name of Pole, on becoming heir to the estates of his cousin, William Pole of Ballyfin, Queen's County, whose mother was daughter of Henry Colley of Castle Carbury, elder brother of Richard Colley Wellesley, first baron Mornington [q. v.] From 1783 to 1790 he sat for Trim in the Irish parliament, and from that date till 1794 represented East Looe in that of Great Britain. In 1801 he was elected for Queen's County, which he continued to represent for twenty years. On 13 May 1802 he seconded Hawkesbury's motion approving the treaty of Amiens, and in the following July was named clerk of the ordnance. In the succeeding sessions he vigorously defended the policy of his brother, Lord Wellesley, in India, courting a full investigation of the charges made against him by James Paull [q. v.] and others. He also defended Melville when impeached. On the return of the tories to power after the death of Fox, Wellesley-Pole resumed his former office, but on 24 June 1807 exchanged it for the secretaryship to the admiralty. In October 1809 he was appointed by Perceval chief secretary for Ireland and a privy councillor. His predecessor in the office had been his own brother, Sir Arthur Wellesley, whose elevation to the peerage Lord Colchester credits him with obtaining. Wellesley-Pole's period of office was marked by the renewal of the movement for catholic emancipation. His attempts at repression by the enforcement of the Convention Act, his circular to Irish magistrates, and the proclamation which followed it, and his unsuccessful prosecution of the delegates to the Dublin convention, were much criticised in parliament and earned him great unpopularity. Wellesley-Pole was the chief supporter of Perceval in his resistance to the concession of the catholic claims. On 31 Dec. 1811 he drew up a confidential memorandum on the subject addressed to the home secretary, but intended for circulation in the cabinet. In this paper (which is printed in full in Walpole's Life of Perceval) Wellesley-Pole based his opposition to concessions largely upon a book recently issued by the catholics, in which they had claimed three-fourths of the offices in Ireland.
In March 1812 Perceval proposed his name for admission to the cabinet, but the regent peremptorily refused unless the Marquis Wellesley were head or part of the government (Buckingham, Court and Cabinets of the Regency, i. 268). In the following month Wellesley-Pole is said to have made ‘a miserable figure’ in the debate on Grattan's motion for a committee on the catholic claims. But in May 1812 Wellesley-Pole became reconciled with Wellesley, and formally acquiesced in the latter's liberal views on the catholic claims (ib. p. 328). In August he resigned the chief-secretaryship and the chancellorship of the Irish exchequer, and was succeeded by Peel. He remained in opposition to Lord Liverpool until on 28 Sept. 1814 Liverpool appointed him master of the mint, and gave him a seat in his cabinet. In April of the following year Wellesley-Pole went with Lord Harrowby to Brussels to confer with Wellington as to the disposition of the allies and the arrangements for the coming campaign.
On 17 July 1821 he was created a peer of the United Kingdom with the title of Baron Maryborough. He shared Wellington's disapproval of Lord Wellesley's policy in Ireland, but stood alone in the cabinet in opposing a measure for the enforcement of the laws against the secret societies (Courts and Cabinets of George IV, i. 441–2). In August 1823 he resigned the mint and left the cabinet to make room for Canning's adherent, William Huskisson [q. v.] He thought himself ‘shamefully deceived, ill-used, and abandoned’ (ib. ii. 7), though he was made master of the buckhounds as an honourable retirement. He never again held cabinet office, though he was postmaster-general in Sir Robert Peel's short ministry of 1834–5. On the death of the Marquis Wellesley in 1842 he succeeded to the Irish earldom of Mornington. He died in Grosvenor Square, London, on 22 Feb. 1845.
Mornington married, on 17 May 1784, Katherine Elizabeth, daughter and coheiress of Admiral John Forbes (1714–1796) [q. v.] She survived to the age of ninety-one, dying on 23 Oct. 1851. Of their three daughters, Mary Charlotte Anne married Sir Charles Bagot; Emily Harriet, Field-marshal Fitzroy James Henry Somerset, first baron Raglan [q. v.]; and Priscilla Anne, John Fane, eleventh earl of Westmorland [q. v.]
The son, William Pole Tylney Long-Wellesley, fourth Earl of Mornington and second Baron Maryborugh (1788–1857), born on 22 June 1788, assumed the additional names of Tylney-Long on his marriage in 1812 with Catherine, sister and coheiress of Sir James Tylney-Long, bart., of Draycot, Wiltshire. The name is commemorated in a well-known line of ‘Rejected Addresses:’
Bless every man possess'd of aught to give;
Long may Long Tilney Wellesley Long Pole live.
(Loyal Effusion by W. T. F[itzgerald]). The lady had, besides a large personalty, estates
