Nigel Farage has revealed he is "thrilled" that Article 50 has now been triggered.
On Wednesday, a written letter was formally handed over to the President of the European Council Donald Tusk from Theresa May, invoking Article 50 of the Lisbon Treaty which begins the two year process of leaving the European Union.
The former Ukip leader had campaigned for years to get Britain out of the EU and was successful when the country voted to leave on the 24 June last year.
Speaking in Westminster, Farage said: "I'm thrilled, because I know that at 12.30 today we are past the point of no return. There'll be lots of arguments and debates over the next two years but we are leaving so I couldn't be happier really.
"I shall go for a pint of something and think to myself that after 25 years of slog perhaps it was all worth it.
"We are in a very, very strong position you know, we are the biggest export market for the Eurozone in the world, they even call us treasure island.
"That's how important the UK economy is to the German car manufacturers and the French wine producers. So, the Prime Minister goes into this with a very strong hand indeed."