Key dates in Britain's relationship with the EU

(LONDON) - Prime Minister David Cameron could agree a reform package at a summit in Brussels starting Thursday, paving the way for a referendum on whether Britain should leave the European Union as early as June.

Here are some of the key dates in Britain's often troubled relationship with the EU over recent decades:

August 9, 1961

Britain makes its first formal application to join what was then the European Economic Community (EEC) under then Conservative prime minister Harold Macmillan.

January 14, 1963

France's then president General Charles de Gaulle vetoes the application for the first time. He does the same thing for a second application on November 27, 1967.

January 1, 1973

Britain finally enters the EEC at the same time as Ireland and Denmark, after de Gaulle has left office.

June 5, 1975

In a referendum on membership of the EEC, Britain votes "Yes" by slightly over 67 percent.

November 30, 1979

Prime minister Margaret Thatcher demands a rebate of Britain's contribution to the European budget in a speech which became best known for a phrase attributed to her as: "I want my money back!"

September 20, 1988

Thatcher gives a landmark speech in the Belgian city of Bruges which has come to be seen as a rallying cry among eurosceptics for less European integration.

February 7, 1992

The Treaty of Maastricht, which underpinned the next stage of European integration, is signed. Britain secures an opt-out from joining the single European currency.

July 23, 1993

Prime minister John Major holds a confidence motion in his government over the Maastricht Treaty after serious infighting in his Conservative party over Europe. He is caught on camera calling eurosceptic ministers plotting against him "bastards".

April 20, 2004

Labour prime minister Tony Blair, a europhile, announces his intention to hold a referendum on the European constitution. It is never held, after France and Denmark rejected it.

January 23, 2013

Cameron promises a referendum on EU membership if his Conservative party wins the next general election.

May 22, 2014

The anti-EU UK Independence Party (UKIP) tops the polls in European elections with more than 26 percent of the vote, securing 24 seats.

May 7, 2015

Cameron's Conservatives win a surprise clear majority in the general election, clearing the way for a referendum to be held.