Henry Addington, 1st Viscount Sidmouth (30 May 1757 – 15 February 1844) was a British Tory statesman who served as prime minister of the United Kingdom from 1801 to 1804 and as Speaker of the House of Commons from 1789 to 1801.

Addington is best known for obtaining the Treaty of Amiens in 1802, an unfavourable peace with Napoleonic France which marked the end of the Second Coalition during the French Revolutionary Wars.

In March 1801, William Pitt the Younger resigned from office, ostensibly over the refusal of King George III to remove some of the existing political restrictions on Roman Catholics in Ireland (Catholic Emancipation), but poor health, failure in war, economic collapse, alarming levels of social unrest due to famine, and irreconcilable divisions within the Cabinet also played a role.

He increased the forces, provided a tax base that could finance an enlarged war and seized several French possessions.

Addington also strengthened British defences against a French invasion through the building of Martello towers on the south coast and the raising of more than 600,000 men at arms.

[4] In 1802, Addington accepted an honorary position as vice-president for life on the Court of Governors of London's Foundling Hospital for abandoned babies.

Addington's greatest failing was his inability to manage a parliamentary majority by cultivating the loyal support of MPs beyond his own circle and the friends of the King.

That, combined with his mediocre speaking ability, left him vulnerable to Pitt's mastery of parliamentary management and his unparallelled oratory skills.

However, when Melville resigned as First Lord of the Admiralty in July 1805, Pitt broke his promise by having Sir Charles Middleton appointed instead of Buckinghamshire.

Addington was opposed to a limited measure of Catholic Emancipation, which the Cabinet was considering despite the opposition of King George III.

As Home Secretary, Addington countered revolutionary opposition, being responsible for the temporary suspension of habeas corpus in 1817 and the passage of the Six Acts in 1819.

Addington maintained homes at Upottery, Devon and Bulmershe Court, in what is now the Reading suburb of Woodley, but moved to the White Lodge in Richmond Park when he became prime minister.