Returning to Britain he became active in politics, supporting conciliatory measures for the Americans, and the removal of government interference from the affairs of the East India Company.

Returning to active naval service with a lucrative posting as commodore, he cruised with success off Portugal, and was then entrusted with a secret mission to capture the Dutch Cape Colony.

He became a director of the East India Company towards the end of his life, before illness forced him to retire from business and politics shortly before his death in 1787.

He served in the War of the Austrian Succession, spending some time aboard HMS Canterbury, where he gained a reputation for bravery for an instance when he boarded an enemy fireship so that it could be towed away from a British squadron off Port Louis, Hispaniola.

He was however soon court-martialed for "insubordination and disobedience", and though he was found guilty his record of gallantry in combat was taken into account, and he was given a reprimand in 1757 and ordered to resume his duties.

[1] Johnstone went on to serve aboard HMS Dreadnought, seeing action at the Battle of Cap-Français on 21 October 1757 and receiving praise for his bravery from the squadron's commander, Commodore Arthur Forrest.

[1] His combative nature was also demonstrated in 1758 when, while serving as first lieutenant aboard HMS Trial, he demanded a court martial of his captain Thomas Cookson for alleged incompetence in sailing the ship.

[1] She was initially assigned to carry out escort duties in the North Sea, during one of which Johnstone was faced with a mutiny, which he skilfully put down with minimal loss of life.

[7] Johnstone was appointed colonial governor of West Florida in November 1763 by the Prime Minister, John Stuart, 3rd Earl of Bute.

[1] Johnstone took up his position eagerly, feeling that his new province's strategic location would give it a profitable future, and envisaging West Florida as 'The Emporium of the New World'.

[1] By now Johnstone had been frustrated in his hopes for commercial prosperity in the region, and enjoyed little popular support from civil society, and so decided to apply for a leave of absence.

He continued to be active in the politics of the East India Company, using his parliamentary position to make speeches attacking the North Ministry's schemes for Indian reform, and laying the blame for the chaos in Bengal at Clive's door.

He was particularly skilled at denunciations and obstructing legislation, attacking the 1773 Tea Act as 'criminally absurd', and argued that the Boston Port Bill would unite Americans against Britain.

[1] He tended towards pragmatism on other affairs, believing that while taxing American colonists was legal, it was inexpedient, and that sending British troops to America would be ultimately fruitless and that to maintain order would require the garrisoning of forces in the colonies at great expense.

[9] Johnstone's stance on conciliation probably led to his selection by North to form part of the peace commission sent to America in 1778 under Frederick Howard, 5th Earl of Carlisle.

In his communications he made vague hints of rewards to those who helped secure this outcome, and was eventually accused of attempting to bribe American general Joseph Reed with 10,000 guineas.

[1] In 1779 Johnstone was offered, and accepted, a post as commodore of the Lisbon Station, despite his previous attacks on the ministry, and his support for conciliation over military intervention.

[1] He was promised an assignment on the Portuguese station, before which he cruised off the French coast in his flagship HMS Romney, looking for evidence of invasion preparations.

[1] Hardy instead preferred to avoid action at first, wearing down the enemy fleet at sea while his own continued to refit and resupply from the naval bases along the English coast.

Hardy's tactics were successful, and rather than confront a fresh and well-equipped British fleet, the enemy armada abandoned their plans and returned to French ports.

[7][10] Despite these successes he still tried to maintain his influence in politics, suggesting that Spain be offered Gibraltar in exchange for leaving the war, but achieved no apparent backing or result.

[1] Johnstone was then given command of a squadron that was assigned to carry out an expedition to the River Plate, but in 1780 the Dutch entered the war against Britain and allied with France.

[11][12] He further hampered his ability to fight his ships by sending his best men ashore to collect water, and leaving his decks encumbered with lumber and casks.

Taking advantage of the situation he quickly ran up to HMS Isis with his 74-gun ships Annibal and Héros, and the 64-gun Artésien, fired broadsides into her, and raised the French colours.

[15] After two hours of heavy cannonading the French found themselves in a dangerous position, as Annibal lost her mizzen mast, followed shortly afterwards by her main and foremasts.

[15] He brought Héros in to tow Annibal to safety and made for the open sea, taking with him as prizes the East Indiamen Hinchinbroke and Fortitude, the fireship Infernal, and the storeship Edward.

[19] Having failed in his objective to capture the Cape, Johnstone decided to send the troops and supplies on to the East Indies station, detaching his best warships under Captain James Alms of HMS Monmouth to escort them, while he returned to Britain with the ships Romney, Jupiter, Diana, Jason, Terror, Infernal, one light cruiser, two victuallers, and the Dutch prizes.

[1] Johnstone attempted to place much of the blame for his delay in chasing the French on a subordinate, Captain Evelyn Sutton of HMS Isis, and deprived him of his command and substantial prize money.

[1] He opposed Charles James Fox's proposals for tighter controls on the company, but in a move contrary to his earlier views, supported William Pitt the Younger's scheme.

George Johnstone had achieved small-scale success as a naval officer, serving with undoubted courage, but had not been able to succeed when given a major command.