The United Kingdom triggered Article 50 today (29 March), beginning an unprecedented two-year period of tough negotiations that will end in Britain leaving the European Union.

Sir Tim Barrow, the UK’s ambassador to the EU, hand-delivered a letter, the formal notification of the start of the legal process to take Britain out of the bloc, at 1.30PM.

He handed the six-page letter, signed by UK Prime Minister Theresa May, to European Council President Donald Tusk. It was couriered by Eurostar to Brussels last night with a guard.

Tusk told reporters in a packed press conference, “There is no reason to pretend that this is a happy day neither in Brussels nor in London.

“There is nothing to win in this process and I am talking about both sides. In the essence, this is about damage control.

“What can I add? We already miss you. Thank you and goodbye.”

The Council issued a statement acknowledging the receipt of the letter. As euractiv.com exclusively reported today, it said that “We regret the United Kingdom will leave the European Union, but we are ready for the process that will now have to follow.”

Tusk said that Brexit had cemented the remaining EU-27 together. He described that unity as a paradox.

“We will remain determined and united in the future and also in the difficult negotiations ahead,” said a wistful Tusk.

As the letter was handed over, UKIP MEPs celebrated with beer, cava and cakes at the Old Hack pub opposite the Commission’s Berlaymont building.

At the same time in London, Theresa May addressed the House of Commons in Westminster.

May promised her ambition was a “new, deep and special partnership” with the EU. And she conceded that the UK would no longer be a member of the single market, after admitting that London could not pick and choose among the four freedoms available to EU member states.

But she was heckled badly when she said the world “perhaps now more than ever needs the liberal democratic values of Europe”.

The triggering of Article 50 came nine months after Britain voted to leave the EU in a 23 June referendum.

Although the EU has steadily grown to 28 member states over its 60 years, this is the first time that such an influential country has left the bloc.

Britain, which joined the European Economic Community 1973, is the second biggest contributor to the EU budget.

Tusk will tonight travel to Malta to join the European People’s Party summit. Commission President Jean-Claude Juncker and the Commission’s chief Brexit negotiator Michel Barnier are also on Valetta.

Juncker will react to the notification of Article 50 at a press conference with Maltese Prime Minister Joseph Muscat at about 5.30PM.

At the same time, European Parliament President Antonio Tajani and Guy Verhofstadt, the Parliament’s Brexit negotiator, will give a press conference.

On Friday (31 March), Tusk will issue draft negotiating guidelines to be agreed by the EU-27. They will be finalised at a special summit on 29 April in Brussels.

The guidelines are instructions for the Commission on how to handle the divorce talks.

Today’s Council statement appeared to signal that no discussions over a free trade agreement were finalised.

Barnier has said he wants the agreement finished by October 2018. This would give time for member states and the European Parliament to ratify the deal before the March 2019 deadline for Britain to leave.

Failure to have a withdrawal agreement could lead to Britain crashing out of the bloc with dire consequences, Barnier warned last week.