LONDON — It took Britain more than a decade of trying to join the European club. It’s now got just two to get out and strike a new relationship.

If anyone thinks that will be easy for Britain, a look back to its entry half a century ago will show how difficult and protracted talks with the EU can be.

Successive British governments slogged away at trying to convince the original six members — Belgium, France, Italy, Luxembourg, the Netherlands and West Germany — to let it into what was then the European Economic Community. Membership in 1973 took 12 years of on-and-off discussions that at various times humbled the British.

Prime Minister Harold Macmillan got so distraught he confided in his diary in 1963 that “all our policies at home and abroad are in ruins” after French President Charles de Gaulle vetoed Britain’s first bid to join. De Gaulle would torpedo Britain’s second attempt four years later, too.

“Boy, was it tough,” said Piers Ludlow, a historian at the London School of Economics who is a specialist on Britain’s postwar relations with Europe.

The past talks highlight some of the challenges Britain faces today. While the international political situation is different, the negotiations promise to be even trickier: with far more EU members involved and more complex and interdependent economies.

British Prime Minister Theresa May Wednesday formally began the divorce talks with the EU. Her government is hoping to settle the exit terms alongside talks over the creation of a “deep and special partnership.” The EU wants to first reach a deal on the exit deal and has insisted that any future relationship must be seen to be inferior to full membership.