[1] Educated briefly at Westminster School, Keppel went to sea at the age of ten, and had already five years of service to his credit when he was appointed to Centurion and sent with Lord Anson round the world in 1740.

[1] In June 1747 he ran his ship, the Maidstone, ashore near Belleisle while chasing a French vessel, but was honourably acquitted by a court martial, and reappointed to another command,[2] the fourth-rate Anson.

When, on 11 May 1749, Keppel sailed from Plymouth to the Mediterranean, as Commodore commanding the Mediterranean Fleet,[4] (with his pennant in his old ship HMS Centurion intending to persuade the Dey of Algiers to restrain the piratical operations of his subjects[2]) Reynolds travelled with him as far as Menorca and there painted the first of his 6 portraits of Keppel,[nb 1] along with others of officers of the British garrison there.

[1] In 1757 he had formed part of the court martial which had condemned Admiral John Byng, but was active among those who endeavoured to secure a pardon for him; but neither he nor those who had acted with him could produce any serious reason why the sentence should not be carried out.

[1] In March 1761, Keppel transferred to the third-rate HMS Valiant and was put in command of a squadron to reduce Belle Isle, which was successfully completed in June 1761.

As a member of Parliament, in which he had a seat for Chichester from 1755 until 1761, Windsor from 1761 until 1780, and then for Surrey from 1780 to 1782, Keppel was a Whig partisan, hostile to the King's Friends.

When Keppel was promoted to full admiral on 29 January 1778[12] and appointed to command the Western Squadron, the main fleet prepared against France, he thought the First Lord would be glad for him to be defeated.

[2][1] Prior to 1778 Keppel failed to persuade Sandwich to ignore technical difficulties and "copper sheath only a few ships"; he was later possibly unfairly to make political capital out of this in The London Magazine, March 1781.

[2][1] A column was built in the late 18th century to commemorate his acquittal, commissioned by Charles Watson-Wentworth, 2nd Marquess of Rockingham and designed by John Carr.

[14] When the North ministry fell in 1782 he became First Lord of the Admiralty, was raised to the peerage as Viscount Keppel, of Elveden in the County of Suffolk,[15] and sworn of the Privy Council.

He finally discredited himself by joining the Coalition ministry formed by North and Fox, and with its fall disappeared from public life in December 1783.

[1] Burke, who regarded him with great affection, said that "he had something high in his nature, and that it was a wild stock of pride on which the tenderest of all hearts had grafted the milder virtues".