Chaplin served with the Coldstream Guards in the Peninsula and was severely wounded during the assault on San Sebastián in 1813, for which he received a pension and the war medal with one clasp. He subsequently saw action in the Netherlands and the south of France. At the 1826 general election he came forward for Stamford as the nominee of its patron, the 2nd marquess of Exeter, who had returned his elder brother Charles, 1809-12. He declared himself a ministerialist and boasted of his family connection with the corporation and his brother’s past services, but he was vilified by John Drakard, editor of the Stamford News, for his ‘municipal subserviency’. On the hustings he stated his opposition to Catholic emancipation. He was returned unopposed with Exeter’s brother Lord Thomas Cecil. That August he purchased a lieutenant-colonelcy.
Chaplin voted against Catholic relief, 6 Mar. 1827, 12 May 1828. He divided for the spring guns bill, 23 Mar. 1827. He was in the minorities against revision of the corn laws, 2 Apr., the disfranchisement of Penryn, 7 June, and the Coventry magistracy bill, 18 June. It was probably he, rather than his brother, now the county Member, who presented the Stamford petition for agricultural relief, 2 Apr. 1827.
At the 1830 general election Chaplin offered again for Stamford. Responding to a local challenger, he denied that he had stooped to coercion or ‘oppressed the voters’ and defended his conduct in the House, claiming that he had ‘nearly as often voted against the ministry’ as his opponent had voted for them. He was returned after a contest.
