The United Kingdom is due to leave the European Union — an economic and political partnership of 28 countries — bringing to an end 46 years of British membership.

Brexit is set to be the most important constitutional shake-up the UK has known since it joined the six-nation European Economic Community in 1973, and represents the first time the European institution has lost a member.

The process has plunged the UK into its worst political and constitutional crisis since the Second World War. The country had been due to leave the EU on March 29, 2019, but the revised departure date is now October 31 after gridlock in parliament twice forced an extension.

It was followed by a summer of further British political turmoil — which saw Boris Johnson replace Theresa May as Conservative prime minister.

The UK’s new nationalist leader says he is determined the UK will leave the EU at Halloween, with or without an exit deal. Another delay has looked likely, however, after the UK parliament legislated to try to block a disruptive “no-deal Brexit”. A key summit of EU leaders takes place on October 17-18.