Lascelles, who joined the army at the age of 17, was slightly wounded by an exploding shell while bearing the standard of the second battalion of the Grenadier Guards at Waterloo. He was injured again in 1823 when a gun burst in his hands as he was shooting sea fowl off Cowes. By September that year he had reportedly recovered and was accompanying his younger brother William on a ‘drawing expedition’ to Switzerland.
He was certainly a very lax attender, who cast no recorded votes in the 1827 session. He presented a petition complaining of the Malt Act, 22 Feb. 1828. In his only known speech, 3 Mar., he urged the rejection of the Wakefield and Ferrybridge canal bill, maintaining that the House was bound to do so as long as the Aire and Calder Canal Company ‘perform their contract’. He divided against Catholic relief, 12 May. He voted with the duke of Wellington’s government against reduction of the salary of the lieutenant-general of the ordnance, 4 July 1828. In February 1829 Planta, the patronage secretary, listed him as one who was ‘opposed to the principle’ of Catholic emancipation, but he gave no recorded votes that session. His name does not appear in the lists compiled that autumn by the Ultra leader Sir Richard Vyvyan*. He was granted three weeks’ leave on account of illness in his family, 10 Mar. 1830. He returned to vote against Jewish emancipation, 5 Apr., 17 May. He divided for abolition of the death penalty for forgery, 7 June 1830. He was again returned for Northallerton at the general election that summer. The ministry regarded him as one of their ‘friends’, but he was absent from the crucial division on the civil list, 15 Nov. 1830. He divided against the second reading of the Grey ministry’s reform bill, 22 Mar., and for Gascoyne’s wrecking amendment, 19 Apr. 1831. At the ensuing general election he made way for William at Northallerton. According to the Whig Thomas Creevey*, he had intended to contest Yorkshire but his father had withdrawn him.
Lascelles may have been the ‘son of Lord Harewood’ whom the Conservatives of Pontefract had reportedly ‘been trying to prevail on ... to bleed ... without success’ in the autumn of 1832.