1721    Sir Robert Walpole enters office as the first Prime Minister of the United Kingdom under King George I.

1742    Spencer Compton, Earl of Wilmington, becomes British Prime Minister.

1743    Henry Pelham becomes British Prime Minister.

1782    Charles Watson-Wentworth, 2nd Marquess of Rockingham becomes Prime Minister of the United Kingdom.

1830    Charles Grey, (2nd Earl Grey), became Prime Minister of the United Kingdom.

1908    H. H. Asquith of the Liberal Party takes office as Prime Minister of the United Kingdom, succeeding Sir Henry Campbell-Bannerman

1924    Ramsay MacDonald becomes the first Labour Prime Minister of the United Kingdom.

1943    World War II: British Prime Minister Winston Churchill and U.S. President Franklin D. Roosevelt set Monday, May 1, 1944 as the date for the Normandy landings ("D-Day"). It would later be delayed over a month due to bad weather.

1943    British Overseas Airways Corporation Flight 777 is shot down over the Bay of Biscay by German Junkers Ju 88s, killing actor Leslie Howard and leading to speculation the downing was an attempt to kill British Prime Minister Winston Churchill.

1945    World War II: the leaders of the three Allied nations, Prime Minister of the United Kingdom Winston Churchill, President of the United States Harry S Truman and Soviet Premier Joseph Stalin, meet in the German city of Potsdam to decide the future of a defeated Germany.

1947    Muhammad Ali Jinnah is recommended as the first Governor-General of Pakistan by British Prime Minister Clement Attlee.

1955    Winston Churchill resigns as Prime Minister of the United Kingdom amid indications of failing health.

1960    British Prime Minister Harold Macmillan speaks of the "a wind of change" of increasing national consciousness blowing through colonial Africa, signalling that his Government was likely to support decolonisation.

1974    The house of former British Prime Minister Ted Heath is attacked by members of the Provisional IRA.

1976    British Prime Minister Harold Wilson resigns, citing personal reasons.

1978    British Prime Minister James Callaghan announces that he will not call a general election for October, considered to be a major political blunder (see Winter of Discontent, United Kingdom general election, 1979)

1979    Margaret Thatcher becomes the first female Prime Minister of the United Kingdom.

1984    Brighton hotel bombing: The Provisional Irish Republican Army attempt to assassinate Prime Minister Margaret Thatcher and her cabinet. Thatcher escapes but the bomb kills five people and wounds 31.

1985    The Anglo-Irish Agreement is signed at Hillsborough Castle by British Prime Minister Margaret Thatcher and Irish Taoiseach Garret FitzGerald.

1987    British Prime Minister Margaret Thatcher and President of France François Mitterrand sign the agreement to build a tunnel under the English Channel (Eurotunnel).

1990    British Prime Minister Margaret Thatcher withdraws from the Conservative Party leadership election, confirming the end of her premiership.

1993    History of Northern Ireland: The Downing Street Declaration is issued by British Prime Minister John Major and Irish Taoiseach Albert Reynolds.

1994    Tony Blair is declared the winner of the leadership election of the British Labour Party, paving the way for him to become Prime Minister after the 1997 general election.

1998    Tony Blair becomes the first Prime Minister of the United Kingdom to address the Republic of Ireland's parliament.