Article 50 of the Lisbon treaty sets out how an EU country might voluntarily leave the union. The wording is vague, almost as if the drafters thought it unlikely it would ever come into play.

The Scottish cross-bench peer who wrote Article 50 - the procedure by which the UK would leave the EU - believed it was "not irrevocable". In a BBC interview, Lord Kerr of Kinlochard said the UK could choose to stay in the EU even after exit negotiations had begun.

Today, therefore, I am writing to give effect to the democratic decision of the people of the United Kingdom. I hereby notify the European Council in accordance with Article 50 (2) of the Treaty on European Union of the United Kingdom’s intention to withdraw from the European Union.

If the Liberal Democrats were to secure a majority in December, they would revoke Article 50, cancelling Brexit.

Article 50

Meaning

Noun