John Jeffreys Pratt, 2nd Earl and 1st Marquess Camden (11 February 1759-8 October 1840), only son of the 1st Earl, was educated at Trinity College, Cambridge. In 1780 he was chosen member of parliament for Bath and he obtained the lucrative position of teller of the exchequer, an office which he kept until his death, although after 1812 he refused to receive the large income arising from it. In the ministry of William Pitt, Pratt was successively a lord of the admiralty and a lord of the treasury; then, having succeeded his father in the earldom in 1794, he was appointed Lord Lieutenant of Ireland in 1795. Disliked in Ireland as an opponent of Roman Catholic emancipation and as the exponent of an unpopular policy, Camden's term of office was one of commotion and alarm, culminating in the rebellion of 1798. Immediately after the suppression of the rising he resigned, and in 1804 became Secretary of State for War and the Colonies under Pitt, and in 1805 Lord President of the Council. He was again Lord President from 1807 to 1812, after which date he remained for some time in the cabinet without office. In 1812 he was created Earl of Brecknock and Marquess Camden. He died on 8 October 1840, and was succeeded by his only son, George Charles (1799-1866).

|- style="text-align: center;" | width="30%" |Preceded by:
Lord Hobart | width="40%" style="text-align: center;" |Secretary of State for War and the Colonies
1804–1805 | width="30%" |Succeeded by:
Viscount Castlereagh

|- style="text-align: center;" | width="30%" |Preceded by:
The Viscount Sidmouth | width="40%" style="text-align: center;" |Lord President of the Council
1805–1806 | width="30%" |Succeeded by:
The Earl Fitzwilliam

|- style="text-align: center;" | width="30%" |Preceded by:
The Viscount Sidmouth | width="40%" style="text-align: center;" |Lord President of the Council
1807–1812 | width="30%" |Succeeded by:
The Viscount Sidmouth