He later agreed the 1739 Convention of Pardo resolving trade and boundary issues in the Caribbean, but political opposition in England meant it was never ratified, leading to the 1739 to 1748 War of Jenkins' Ear.

[4] Rolfe was also election agent for Sir Robert Walpole, British Prime Minister from 1721 to 1742; this connection helped the careers of both Benjamin and his younger brother.

Family connections brought him to the notice of Secretary of State and Norfolk magnate, Viscount Townshend (1674–1738), who sent him to Madrid in 1723, first as an officer of the South Sea Company, then Consul from 1724.

[6] The South Sea Company was established to hold commercial rights awarded to Britain in the 1713 Treaty of Utrecht, allowing access to the closed markets of Spanish America.

[9] The real benefit was in carrying smuggled goods that evaded customs duties, demand from Spanish colonists creating a large and profitable black market.

'[11] The Spanish resented being forced to open their colonial markets, partly due to the prevailing economic theory of mercantilism, which viewed trade as a finite resource.

British foreign policy was overseen by Pelham's younger brother, the Duke of Newcastle, who saw this as an opportunity to break the Bourbon alliance, and improve Britain's position in the War of the Austrian Succession.

[15] After the 1748 Treaty of Aix-la-Chapelle ended the war, Keene resumed his position in Madrid; he quickly developed a good relationship with Ferdinand and his ministers, who shared Newcastle's aim of moving Spain away from France and closer to Britain.

He died in Madrid in 1757, and was replaced by George Hervey, 2nd Earl of Bristol, who did not have the same influence; Charles III of Spain succeeded Ferdinand in 1759, and in 1762 he entered the war on the side of France.