Moore ‘was a great favourite with his uncle’ Lord Hertford, who brought him into Parliament and in August 1807 asked Lord Hawkesbury to provide for him, in view of the fact that Lord Henry’s elder brother was insane and his father’s means of providing for his younger children were limited. Government raised no objection when Lord Drogheda was prepared to resign his office of joint muster master general in his son’s favour. It was a sinecure shared with William Bagwell which, according to Peel in 1818, ‘until the reductions in 1815-16 produced £5,000 per annum on an average of eight years, now £1,000 on an average of two years’. Before this arrangement was made for him, Moore had applied in June 1807 to succeed to Lord Castlecoote’s militia command in Ireland.
Moore made no mark in Parliament, supporting government by vote when present, notably on the Scheldt question in 1810. When Hertford’s Members opposed government on the Regency question in January 1811, he diplomatically stayed away.
After Hertford had returned him for Lisburn in 1812, Moore declared in February 1813 that he would offer for the Queen’s County, of which he also desired to become governor and custos, to the embarrassment of government, who had to weigh his claims against those of William Wellesley Pole, then out of office. In 1814 he was named sheriff, but subsequently gave up his pretensions to the county.
Moore intended to offer for Drogheda at the ensuing election, but government were unable to secure him the Foster interest there and he gave it up.
