Coote was nephew and heir to the celebrated general of the same name and likewise pursued a military career. He served in the American war, in the West Indies (1793, 1795), in the Netherlands (1798 and 1799) and subsequently in Egypt, where his services earned him public thanks and his KB in 1802. He was prevented from embarking on a South American expedition by the peace. In 1790 he had made a bid to come into Westminster on Lord Camelford’s interest as a friend of Pitt’s ministry. He had been Member for Ballinakill (1790-7) and, on the family interest, for Maryborough (1797-1800) in the Irish parliament, but had vacated the latter to enable his elder brother to return a Member who could attend in support of the Union. When his brother became a peer of Ireland in March 1802, Coote was invited to stand for the Queen’s County in his place. He declined from want of preparation and to avert a contest, although Addington’s government were prepared to back him on the occasion, without pledging themselves for the next general election. Addington’s brother-in-law Charles Bragge being a relative of Coote’s stepmother, Coote had a personal link with administration, and the viceroy’s half-brother Charles Yorke recommended him as ‘one of the most efficient and distinguished heroes of Aboukir and Alexandria ... really a very amiable and worthy man, besides being a most steady and excellent officer. One has only to regret that he ... [has] not yet been noticed ... A red ribband and an old regiment is the least that can be given to such a man as Coote.’ After negotiations with the Castle, Coote stood down until the general election, on his brother’s advice.
He was returned unopposed at the general election of 1802 and supported government. On 8 Dec. 1802 he advocated provision for an expeditionary force in defence proposals. The chief secretary assured Addington that he would find Coote a useful ally against his Irish critics the Hely Hutchinson family, ‘should things go wrong on foreign politics or military matters’. Coote voiced his approval of the Irish militia bill, preferring recruitment by bounty rather than by ballot, and paid tribute to the militia’s services, 16 Mar. 1803. A month before he had been with the chief secretary ‘very high indeed and full of grievances’ connected with maintaining his interest in the county, but they parted ‘very good friends’.
In August 1807 government learnt that Coote wished to be relieved of his post, as the climate of Jamaica disagreed with his health. He duly returned home and was made second in command in the Walcheren expedition in 1809. His behaviour on this occasion, when he asked to be relieved of his command at Middleburgh owing to the dangerous illness of his eldest daughter, 8 Sept. 1809, was subsequently adduced as evidence of a ‘mind not always sound’. He was examined by the House on his part in the expedition, 27 Feb. 1810. In 1811 he applied for the government of Canada.
Coote, who had failed to maintain his interest in the Queen’s County, was returned after a contest, in which he spent freely, for Barnstaple in 1812. He was regarded as well disposed to government, who were ‘hopeful’ of his support.
Coote had sternly opposed the abolition of flogging in the army, 15 Mar. 1813, and on 25 Nov. 1815 was charged with improperly indulging in flogging with scholars of Christ’s Hospital whom he had paid for the purpose. The lord mayor dismissed the case, Coote ‘reluctantly’ agreeing to donate £1,000 to the school (afterwards returned) but the scandal led to a military inquiry, 18 Apr. 1816. Fourteen Members were among the friends who in a letter to the Duke of York declared that Coote had acted ‘solely from insanity’, attributed cumulatively to heredity, the Jamaican sun and the deaths of his daughters, but Coote was adjudicated eccentric, not insane, 14 May, stripped of his honours and struck off the army list. He had been warned in April that he must retire from Parliament to avoid expulsion, but his brother-in-law William Bagwell, who ‘most foolishly’ published a defence of Coote, made it clear that if Coote were attacked in Parliament, which his family was anxious to avoid, the decision of the military inquiry would be challenged.