[4] In 1738, Johnstone persuaded his father to send him to Saint Petersburg, where he stayed with his mother's uncle, James Hewitt, an expatriate Scot and merchant.

Another uncle, Gustav Otto Douglas (1687–1771), was a Russian general who was born in Sweden, but changed sides after being captured at Poltava in 1709.

[citation needed] His sister Cecilia's marriage into the Rollo family connected Johnstone to the circle of Jacobite gentry in Perthshire.

[citation needed] Johnstone joined the Jacobites under Charles Edward Stuart when they reached Perth in early September 1745.

[10] Johnstone accompanied Lord Ogilvy to Clova, in Angus, and then spent several weeks hiding in the Highlands until he could return to Edinburgh.

His old friend Lady Jane Douglas helped him escape to London, where he watched members of the Jacobite Manchester Regiment being taken to Kennington Common for their execution on 30 July 1746.

[11] Although he had originally intended to return to Russia, Johnstone stayed in Paris until Stuart was expelled from France after the 1748 Treaty of Aix-la-Chapelle.

A recurring theme of his Memoirs is his complaint of unfair treatment as he considered his rank an insult; however, when he arrived at Louisbourg in 1754, he was promoted lieutenant.

[citation needed] Johnstone reportedly deposited his manuscripts in the Scots College, Paris, including Memoirs of the Rebellion in 1745 and 1746, translated into English and published in 1822.

[citation needed] While full of complaints about the injustice of the world and often extremely self-centred, they are lively and include the occasional flash of insight.