| Constituency | Dates |
|---|---|
| Truro | 6 Mar. 1787 – 1790 |
| Winchelsea | 17 Feb. 1794 – 1796 |
| Wendover | 1796 – 1802 |
| Bossiney | 1802 – Dec. 1802 |
| Harwich | 4 Jan. 1803 – 1818 |
Ld. of Treasury Dec. 1800-Mar. 1801 and July 1802-Nov. 1803; sec. to Treasury Mar. 1801–2; jt. paymaster gen. Jan. 1803 – July 1804; P.C. 16 Feb. 1803; commr. for Indian affairs Feb. 1806 – Apr. 1807; under-sec. of state for Home affairs 1812 – 18.
High steward, Harwich 1803 – d.
Hiley Addington ‘while a boy, was left a considerable fortune by a relation’; and he acquired another by marriage.1J. Wilson, Biog. Index. to Commons, 1806, p. 10. His parliamentary career he owed to his brother Henry, whose interests he looked after at Devizes in the general election of 1784.2Hiley to Hen. Addington, Apr. 1784, Sidmouth mss. Pitt wrote to Henry on 14 July 1786 proposing that Hiley might, at no expense to himself, come in for Berwick-on-Tweed, on Lord Delaval’s interest.3Sidmouth mss. Hiley, however, was defeated. Several months later he was returned on Lord Falmouth’s interest at Truro. No speech of his is recorded before 1790; he voted with Pitt in the Regency crisis.
To his brother’s regret, Hiley was not returned in 1790.4Hen. Addington to R. P. Carew, 10 July 1790, Sidmouth mss. He subsequently held several minor ministerial posts, and died 11 June 1818.