| Constituency | Dates |
|---|---|
| New Windsor | 20 Feb. 1797 – 1802 |
| Kilmarnock Burghs of Burghs | 1841 – 1847 |
Capt. 98 Ft. 1780, 59 Ft. 1784 – 90, Berks. fencibles 1795, 85 Ft. 1798; capt.-lt. Windsor foresters 1794 – 95; col. Prince of Wales’s fencible inf. 1799–1802.
Johnston, whose father purchased the Hilton estate with naval prize money, entered the army ‘at an early age’ and served with ‘considerable reputation’ in seven actions against the French in India.1A. Johnston, Gen. Acct. Johnston Fam., 20. In 1790, he stood unsuccessfully for Nottingham, where his regiment was quartered. The death of Henry Isherwood in January 1797 created a vacancy at Windsor, where the King was anxious to preserve the peace of the borough by accommodating any acceptable candidate proposed by the late Member’s supporters, and Johnston was brought forward when their first choice declined. Although neither the King nor Pitt was well disposed towards Johnston, of whom Pitt had ‘no certain accounts and none that promise very favourably’, and both would have preferred the dependable Lord Inchiquin, it was the latter who stood down: Johnston was comfortably returned after a contest forced by a late freelance challenger.2Geo. III Corresp. ii. 1496, 1498.
Johnston voted for the assessed taxes augmentation bill, 4 Jan. 1798, but opposed government on the delay in paying the increase in seamen’s wages, 10 May 1797, and voted for inquiry into the Prince of Wales’s financial claims, 31 Mar. 1802. It was probably he rather than George Johnstone who divided in favour of inquiry into the Ferrol expedition, 19 Feb. 1801. He is not known to have spoken in the House. When a hectic canvass began at Windsor in November 1801, he announced his intention of seeking re-election, but he apparently took few pains to preserve his support and at the dissolution of 1802 was forced to withdraw. He solicited a seat from ministers, unsuccessfully, via Lord Melville, at the 1807 general election.3Windsor Election Handbills (1802), 7, 35; SRO GD51/1/198/1/16.
Johnston, who in 1798 raised a regiment of fencible infantry for general service which was reduced at the peace of 1802, is said to have become insolvent and to have lived within the precincts of Holyrood Abbey. He died at The Hague, 13 Jan. 1844.