The United Kingdom will formally leave the European Union tonight, finally giving effect to the result of the ‘In-Out’ referendum on EU membership held in 2016.

Today is the last day of the United Kingdom’s membership of the European Union. 
It will formally cease to be a member state at midnight tonight, Central European Time, 11pm London – and Irish time. 
The UK prime minister, Boris Johnson, will make an address to the British people shortly before, amid muted official events to mark the moment.
When the Article 50 process expires at 11 tonight, the United Kingdom will become the first state to leave the EU, bringing to an end 47 years of membership.
However, it is leaving with a deal, a withdrawal agreement having been ratified by both parties this week, after a year of political turmoil in Westminster.
Because of that agreement, there will be a transition period until the end of the year, during which nothing will change from a practical point of view. 
But British politicians and Civil Servants will not take part in any further EU business.
Instead they will begin the second phase of the Brexit process, negotiating a new set of relationships with the EU as an external party.
Official events to mark the end of EU membership are low key, the government mindful that almost half the population voted against Brexit.
In Scotland – which recorded the biggest Remain vote – the First Minster will lead a protest march in Edinburgh and there will be a candlelit vigil outside the Scottish Parliament at 11pm.
In London, the biggest public event is an unofficial rally organised by the Brexit Party on Parliament Square, to celebrate the end of the long campaign by it and its predecessor organisation, the UK Independence Party.