| Constituency | Dates |
|---|---|
| Wigan | 1780 – 1784 |
| King's Lynn | 1784 – 1807, 1807 – 24 Feb. 1809 |
Sec. and registrar, Chelsea Hosp. Apr. – Dec. 1783; clerk of estreats c. 1783 – c.1801; high steward, King’s Lynn 1809 – d.
Lt.-col. E. Norf. militia 1780, col. W. Norf. militia 1792 – d.; brevet col. 1794–1803.
Walpole continued to sit for Lynn on the family interest and unopposed. A cousin by marriage of the 3rd Duke of Portland, who first brought him into Parliament in 1780, he acted with the opposition to Pitt in the Parliament of 1784, joined the Whig Club, 3 Apr. 1786, and again voted with them, 12 Apr. 1791 and 1 Mar. 1792, against the Russian armament, as well as being listed favourable to repeal of the Test Act in Scotland in 1791. Subsequently, however, he was one of the Portland Whigs (so listed in December 1792) who, after attending Windham’s ‘third party’ rally of 17 Feb. 1793, did not oppose government during the war with France. In 1794 he was a colonel on active service. He voted against the abolition of the slave trade, 15 Mar. 1796. Only one speech, on militia matters, 13 Dec. 1796,1Debrett (ser. 3), i. 352. can with any certainty be attributed to him, since his brother George was a frequent speaker on the side of opposition and speeches attributed both to General and to Colonel Walpole appear to be his. On 31 Mar. 1802 both brothers voted for inquiry into the Prince of Wales’s financial resources and Horatio had also been in the minority on the civil list two days before.
Walpole voted against Pitt’s additional force bill on that minister’s return to power, June 1804, and was listed ‘doubtful’ by government in September. On 6 Mar. 1805 he voted for Sheridan’s motion for the repeal of the Additional Force Act, and on 8 Apr. voted for the censure and on 12 June for the criminal prosecution of Melville. He was listed ‘doubtful Opposition’ in July. He did not oppose the Grenville ministry, his brother being in office and his father created by them Earl of Orford.2Geo. III Corresp. iv. 3224. He even became a ‘staunch’ supporter of the abolition of the slave trade. He did not vote on Brand’s or Lyttelton’s motions, 9, 15 Apr. 1807. He supported the Portland administration until he succeeded to the title. In the Lords he was an anti-Catholic Tory. He died 15 June 1822.