[2] He was a personal friend of such major cultural figures as the actor David Garrick, the novelist Laurence Sterne, and the French playwright Beaumarchais.

[4][5][6] Educated at Eton College (1725–32) as Viscount Tunbridge, Rochford's school friends included three future secretaries of state, Conway, Halifax and Sandwich.

He inherited strong Whig principles and was a loyal supporter of the Hanoverian Protestant succession, but also admired Sir Robert Walpole's peaceful foreign policy.

However, he had agreed to accept an ordinary Envoy's salary for a probationary period, and this gave him a strong incentive to show zeal and become a thoroughly professional diplomat.

His first negotiations, on behalf of a company of English miners and the Protestant Vaudois communities of the Piedmont Alps, were entirely successful, and he then obtained his full salary.

[9][10] Recalled from Turin for the duration of the Seven Years' War (1755–63), Rochford resumed his career as a courtier, appointed by George II as First Lord of the Bedchamber and Groom of the Stole, highly prestigious posts.

He spent the early 1760s involved in local Essex politics and 'improved' the Park at his St Osyth estate, adding a formal Dutch garden and a maze.

[11] Rochford's secret instructions for his Madrid embassy were mainly concerned with countering French influence over the king, Carlos III, and reporting on Spain's naval reconstruction after her late and disastrous entry into the Seven Years' War.

With strong support from Grenville's administration, Rochford's threats of naval force made the Spanish back down, but gave him a reputation as an anti-Bourbon.

[12] Less successful were his efforts to compel Spain to pay the disputed Manila Ransom, which the French foreign minister Choiseul suggested should be submitted to arbitration.

His friendship with the British consul-general at Madrid, Stanier Porten (uncle of the historian Edward Gibbon) deepened his interest in trade matters, and he used the consuls as well as paid spies to get accurate information about Spain's naval rebuilding.

Though Rochford gave early warning of the likely terms, and paid a spy to get a copy of the draft treaty, the British cabinet led by Lord Grafton was too preoccupied by rioting in London and failed to support their ambassador in Paris.

[17] Britain's main goal at this time was a treaty of alliance with Russia, but the Empress Catherine II and her foreign minister Panin insisted on a hefty subsidy, which Rochford refused.

Instead he persuaded George III to pour secret service money into Swedish politics, to support Russia and undermine French influence.

Britain's envoy at Stockholm, Sir John Goodricke, made adroit use of this money, and helped to maintain Sweden's liberal constitution.

[18] Spain's expulsion of a British garrison from the Falkland Islands in May 1770 sparked a major diplomatic crisis that brought Europe to the brink of war.

Before the creation of separate Home and Foreign offices in 1782, the Southern Secretary carried a heavy burden of domestic responsibilities, including oversight of Ireland.

Rochford played a key role in this crisis, advising caution to the Russians and warning the French that Britain would also send a fleet to the Baltic.

Rochford's most difficult domestic duty as southern secretary was to act on behalf of George III in the painful negotiations of May 1773 with his brother, the Duke of Gloucester, who had secretly married Horace Walpole's niece, Maria Waldegrave, in 1766.

In view of the Royal Marriages Act of 1772, George III regarded this news as a betrayal by his most trusted sibling, and was deeply hurt, refusing at first to make any reply.

Poor health and the bungled arrest of an American banker in London, Stephen Sayre, on suspicion of a plot to kidnap George III, prompted Rochford's retirement on 11 November 1775, with a generous pension and a promise of the 'Blue Ribband' (Knight of the Garter).

On behalf of George III he also undertook secret talks with Beaumarchais, and made a quick trip incognito to Paris to try to persuade the French government to stop sending aid to the American rebels, concluding that France was about to declare open war.

[28] In his youth Rochford was an accomplished horseman and an expert yachtsman, once racing his yacht from Harwich to London against that of Richard Rigby, and was also involved in early Essex cricket matches.

Most famously, he is credited with the first known introduction of the Lombardy poplar to southern England, bringing home a sapling strapped to the centre-pole of his carriage in 1754.

In his Memoirs of the Reign of King George III, Walpole described Rochford as 'a man of no abilities and of as little knowledge, except in the routine of office'.

He was exceptionally well-informed, and his unpublished Plan to Prevent War in Europe (1775) reveals him as a strategic thinker, and one of the most imaginative of Britain's eighteenth century secretaries of state.

[31] Hamish Scott has described Rochford as 'the ablest man to control foreign policy in the first decade of peace [after 1763], a statesman of intelligence, perception and considerable application'.

Historians now agree that the American rebels won the war mainly because Britain's naval resources were too thinly stretched by the involvement of the Bourbon powers.

[33] The earls of Rochford used the arms below, inherited via the founder of their Family Fredrick of Nassau, lord of Zuylestein, illegitimate son of Frederick Henry, Prince of Orange.