He was born in Parliament Close, near to St Giles Cathedral on the Royal Mile in Edinburgh on 25 May 1713, the son of James Stuart, 2nd Earl of Bute, and his wife, Lady Anne Campbell.

Bute furthermore became close to Prince Frederick's widow, Augusta of Saxe-Gotha, the Dowager Princess of Wales, and it was rumoured that the couple were having an affair.

Indeed, one of the Prince of Wales's associates, John Horne Tooke, published a scandalous pamphlet alluding to the liaison, but the rumours were almost certainly untrue, since Bute held sincere religious beliefs against adultery and, by all indications, appeared happily married.

[11] Because of the influence he had over his pupil, Bute expected to rise quickly to political power following George's accession to the throne in 1760, but his plans were premature.

It would first be necessary to remove both the incumbent prime minister (the Duke of Newcastle) and arguably the even more powerful Secretary of State for the Southern Department (William Pitt the Elder).

[12] The Government of the day, buoyed by recent successes in the Seven Years' War, was popular, however, and did well at the general election which, as was customary at the time, took place on the accession of the new monarch.

Next, Bute forced Newcastle's resignation as prime minister when he found himself in a small minority within the government over the level of funding and direction of the Seven Years' War.

[14] Re-elected as a Scottish representative peer in 1760, Bute was appointed the de facto prime minister after the resignations of Pitt and Newcastle, thus ending a long period of Whig dominance.

[16] After peace was concluded, Bute and the King decided that Britain's military expenditure should not exceed its prewar levels, but they thought a large presence was necessary in America to deal with the French and Spanish threat.

[19] He died at his home in South Audley Street, Grosvenor Square, Westminster, from complications of a fall suffered while staying at Highcliffe, and was buried at Rothesay on the Isle of Bute.

[21] According to historian John Naish, the 18th-century expression "Jack Boot" meaning a stupid person originated as disparagement of Stuart's performance as prime minister.

[23] Recognising that the existing buildings were unsuitable, Bute commissioned the neoclassical architect Robert Adam to oversee the redesign of the estate house.