Brexit countdown begins today as Article 50 triggered

The countdown to Britain's exit from the European Union begins today as the UK's ambassador to the economic bloc delivers Theresa May's letter to the European Council in Brussels, announcing the country's intention to initiate a two-year negotiation process for its departure.

The formal notification to the other 27 EU members of Britain's intention to invoke Article 50 of the Lisbon Treaty was signed by May at her 10 Downing Street office last night.

Her ambassador in the EU, Tim Barrow, began his meeting with European Council President Donald Tusk this morning during which he will formally hand over the letter to set the clock for a two-year negotiation process for Britain's relationship with the EU as a non-member.

May chaired a Cabinet meeting this morning and is set to make a statement in the House of Commons confirming that the countdown to Britain's exit from the EU has now begun.

Excerpts from her statement indicate that she will promise to "represent every person in the whole United Kingdom".

"It is my fierce determination to get the right deal for every single person in this country. For, as we face the opportunities ahead of us on this momentous journey, our shared values, interests and ambitions can - and must - bring us together," her statement reads.

"We are one great union of people and nations with a proud history and a bright future. And, now that the decision has been made to leave the EU, it is time to come together," it adds.

Opposition Labour leader Jeremy Corbyn said his party respected the decision to leave the EU and would hold the government to account "every step of the way".

The focus will now shift to No 9 Downing Street in London, which houses the Department for Exiting the European Union headed by Brexit minister David Davis.

Following the notification process, the Great Repeal Bill will be published in Parliament tomorrow to cover the political break from the economic bloc.

On Friday, Tusk is expected to publish the European Council's negotiating guidelines, which will make the course of the so-called "divorce" proceedings for Britain's exit clearer.

The Brexit negotiator on the EU side, Michel Barnier, has said he would like to wrap up the process by September 30, 2018, leaving enough time for it to be ratified by the European Parliament.

The notification of Article 50 marks the first formal step in the direction of Brexit after a referendum in June 2016 in favour of Britain leaving the EU.

Last night, May spoke by telephone to Tusk, EU Commission president Jean-Claude Juncker and German Chancellor Angela Merkel to discuss the move.

Article 50 gives both sides two years to reach agreement, so unless both sides agree to extend the deadline for talks, the UK will have left the EU on March 29, 2019.

The official negotiations with the EU are to begin by mid-May.

The UK government says it wants to carry out both separation and trade talks at the same time, but EU chiefs say the two issues must be handled separately.

The UK has said it wants an "early agreement" to guarantee the rights of EU citizens living in the UK and those of British nationals living in EU countries.

Other issues which are likely to be discussed are things like cross-border security arrangements, the European Arrest Warrant, moving EU agencies which have their headquarters in the UK and the UK's contribution to pensions of EU civil servants - part of a wider so-called "divorce bill" which some reports have suggested could run up to 50 billion pounds.