A guide to how the UK will leave the European Union after the 2016 referendum.Read more
On Thursday the government will publish details of its Great Repeal Bill, which aims to end the supremacy of EU law. The bill will also incorporate existing EU legislation into the UK statute book.
That will be the sequel to a historic day, as the UK formally gave notice of its departure from the EU by invoking Article 50 of the Lisbon Treaty.
UKIP leader Paul Nuttall said: “At the moment we’re doing less trade with the European Union year-on-year - more with the rest of the world”.
The overall value of the UK’s trade with the EU has increased in most years, but if we take trade with the EU as a proportion of the UK’s total trade, there has indeed been a moderate downward trend since its peak in 1992.
However, it’s not a completely consistent pattern. In some recent years the proportion has risen, the year-on-year changes have been fairly small, and trade with the EU is consistently around half of the UK’s overall trade.
Jonathan Bartley, the co-leader of the Green Party, referred to an ongoing case in Dublin, which is seeking to refer to the European Court of Justice the question of whether the triggering of Article 50 can be reversed.
We looked into the issue of whether the UK can change its mind on Article 50 here .
During his interview with Andrew Neil, Jeremy Corbyn said he was against a second referendum on Scottish independence because “there is a £15bn gap between Scottish taxation income and the requirements of Scottish public services”. That is essentially the gap between how much the Scottish Government spends and what it raises through tax.
Scottish government statistics say the Labour leader is right. In 2014-15 Scottish public sector revenue was estimated at £53.7bn - the equivalent of £10,000 per person, and about £400 per person lower than the UK as a whole. Meanwhile, total expenditure by the public sector was £68.6bn. Overall, that’s a gap of £14.9bn between revenue and expenditure.
First Minister Nicola Sturgeon has insisted the "foundations of the Scottish economy remain strong" and that “Scotland's long-term economic success is now being directly threatened by the likely impact of Brexit".
You can read more here.
Liberal Democrat leader Tim Farron is talking about the second referendum his party wants to hold on the terms of the Brexit deal.
This is constitutionally possible, but the government has no plans to hold one and the question of whether Article 50 is irrevocable is the subject of legal dispute.
Lib Dem Tim Farron says the good news for those who are "sad" at Article 50 being invoked is that the European Parliament has confirmed it can be revoked inside the two-year window.
He claims this has thrown a "parachute" to the UK.
Jeremy Corbyn says: "We have great levels of inequality in Britain – amongst the greatest in Europe."
A European Commission study on inequality from 2015 looked into different measures of inequality across the EU
The most widely used measure for income inequality is the Gini coefficient. On that measure, the UK is doing better than 15 other EU countries, and worse than 12 others.
Inequality is greatest in Bulgaria, Cyprus, the Baltic states, Portugal, Romania, Greece and Spain. The most equal countries are Slovenia, Sweden, the Czech Republic, the Netherlands, Belgium and Slovakia.
Jonathan Bartley, the joint leader of the Green Party, says that if Theresa May is serious about uniting the country she would not be pursuing an "extreme version of Brexit".
He says he is "passionate about free movement" and will "defend it to my dying day".
he adds that no one has mentioned climate change, which he says is the biggest issue facing families, in today's debates and statements on Article 50.
UKIP leader Paul Nuttall, whose party is the self-styled "guard dog of Brexit", says he saw "very little" to disagree with in Theresa May's statement earlier.
But he says that "when it comes to walking the walk", the PM "generally fails", claiming things like fishing rights could be "bartered away".
Moving on to other party leaders now. Lib Dem Tim Farron defends his call for another referendum - this time on the terms of the Brexit deal.
We do not know what the deal will look like and the people should not be forced to accept a "stitch up", he says.
On the question of Scottish independence, Jeremy Corbyn says things "could get a bit complicated" if a referendum takes place at the same time as the Brexit negotiations.
If one takes place at all, it would be better for it to be "after Brexit negotiations have been completed," he says.
Labour will be "working out a policy proposal" on immigration, Jeremy Corbyn says. Does he agree with that shadow home secretary Diane Abbott that free movement is a "worker's right"?
He says they both want to end the "grotesque exploitation" of migrant workers.
BBC political reporter
Scary clowns, mad hatters and a giant-headed Theresa May.
Just some of the fancy dress outfits worn by those protesting the triggering of Britain's exit from the EU outside the Houses of Parliament.
"I felt like I needed to come down and remind Parliament, the British public and the world that we are not willing to put up with having Brexit", Eddie Spinx, whose been standing outside Downing Street shouting from a megaphone all day, tells me.
A group of UKIP members all smiles and brightly dressed in purple are celebrating.
"I feel very happy", one tells me.
"The divorce settlement is zero maintenance", adds another.
We've still got two years until we actually leave the EU - and at the moment no signs here of the two sides coming together.
Jeremy Corbyn dismisses claims of a £50bn payment from the UK to leave the EU - he says he does not know where the figure comes from.
Labour will be holding the government to account "all the way through", he says, and he rejects the idea of a second referendum.
"We want to be able to speak for the entire country," he adds.
Is he enthusiastic about Brexit? "Brexit is happening," he replies.
Next up is Labour leader Jeremy Corbyn.
"The reality is, we are leaving the European Union," he says, calling for better support for big UK industries as a result of the negotiations.
He accepts the UK cannot remain in the EU single market and will need to develop a new set of trading relationships, predicting this will be "very complicated".
BBC Radio 5 live
5 live’s reporters have been out and about across the UK, finding out how people are feeling on the day Article 50 is triggered. From a farm on Derbyshire to a tech company in Swansea, this is what people told us.
Asked about the "Brexit dividend" promised by the Leave campaign before the referendum, Theresa May. who backed the rival campaign to stay in the EU, says the UK will be able to decide how it spends "significant sums" currently given to the EU.
Will it go to the NHS, as promised by Vote Leave? "During the referendum there were points made, often very passionately, on both sides of the argument," she says.
"We are now beyond the referendum, we are now at the stage where we are putting this into practice."
Theresa May tells Andrew Neil she wants to keep the same level of co-operation on cross-border security issues after the UK has left the EU.
This has emerged as a talking point following her Article 50 letter, which suggests crime and security co-operation could suffer if Brexit talks fail to reach agreement.
How about the government's comments that the UK could change its "economic model" to stay competitive if no trade deal is reached? ( read more here )
Labour have taken this as a threat to turn the UK into a tax haven, but the PM tells Andrew Neil this amounts to a "straw man argument".
"What it's about is making sure that jobs stay in the UK and new jobs are created here in the UK," she says.
Theresa May says she is confident all the talks can be wrapped up inside two years. Under Article 50, the UK will leave the EU at this point unless both sides agree to an extension of negotiations.
"It's in both sides' interests to do this," the PM says.
Mrs May says that because the UK has been part of the EU makes it easier to reach agreement than "if we were coming at it completely fresh".
Theresa May says she wants trade between the UK and the EU to be "as frictionless and tariff-free as possible".
She says the UK will have a "different relationship" with the EU after Brexit, but that it will "have the same benefits" on trade.
The prime minister says she wants a reciprocal agreement on the rights of the EU citizens in the UK and the UK citizens in the EU as early as possible.
But the reciprocal deal will be complex and will have to cover things like access to healthcare and pensions.
Andrew Neil has been asking about the possibility of the UK having to pay a £50bn exit fee on leaving the EU.
The prime minister wouldn’t discuss figures and stressed that people had voted to stop making large annual payments to the EU. But she didn’t rule out paying an exit fee and she said the UK is a law-abiding nation and that the government would have to look at what its obligations are.
She also said there had been no formal demands, which is not surprising as the official negotiations have not yet started.
Here’s a Reality Check on where that figure comes from.
Andrew Neil asks Theresa May about one of the key themes of the EU referendum - immigration. Will there be a reduction in the numbers, he asks.
"We will see a difference in the numbers coming in," replies the PM.
She says the government will be able to have control and "set the rules" but won't go into detail about the new model, saying a new bill will be brought forward "in due course".
There was loud banging on the tables in support of Theresa May as she went into the meeting of the 1922 committee and again when she left.
After the meeting one senior Tory MP said Mrs May told the gathering that "the task starts now and there's lots of work to do" and she apparently added there are "opportunities for everyone" saying the "referendum was not just about Brexit but about everyone who felt left behind".
"She was great" one MP said as he left, another added she was "good, very good".
In the next few days, the EU will publish a holding statement setting out its initial, draft response to Mrs May's letter.
This document - several pages long - will make clear the EU's key principles for the talks ahead. But its formal negotiating position will be agreed only at a summit of the remaining 27 member states at the end of April, so face-to-face discussions are unlikely until May or even early June, well after the French presidential elections.
There'll be an early row over whether or not Britain's exit deal and future trading relationship with the EU are discussed at the same time or one after another.
There'll be an even bigger row over what outstanding debts the UK may have to pay when it leaves.
Theresa May promised today a "fair settlement". The EU wants £50bn. And there'll also be early talks about the rights of EU citizens living in the UK and Britons in the EU: politically easy; technically very hard.
And as for discussions about any future trade deal, most people expect those will not start until well into the autumn, certainly not before the German elections in September. The hope is that a final Brexit deal could be agreed by October next year so there's time for it be ratified by EU parliaments before the UK leaves in March 2019. That at least is the hope.
Canadian Prime Minister Justin Trudeau has said the UK will remain a "great friend and ally and economic partner" through the Brexit process.
"We will of course work with them as they go through the transition they are embarking upon, he told journalists during a news conference.
"We will continue to look for ways to create closer trade ties and opportunities for better jobs and economic growth that benefits both or countries."
BBC Radio 5 live
The UK could have a "super-Canada deal" with the EU, Conservative MEP David Campbell Bannerman has told BBC Radio 5 live .The Leave means Leave campaigner - a former UKIP MEP - said there had been a "change in tone" from the EU after PM Theresa May made it clear she was not looking for a special "cherry-picking" deal within the single market. "Now we want a clean break, we're not in the single market, not in the customs union, we can have a Canadian-style arrangement with the EU - that works, it's simple," he said. "Canada is a free sovereign nation, it’s got access to 99% of the EU single market, with no freedom of movement, no fee to pay and we’re not asking Canada to join the EU."
BBC News Channel
Lord Heseltine earlier gave what presenter Huw Edwards described as a "forthright" interview on the BBC News Channel.
Here are some of the main points the Conservative peer and former minister - who is a passionate supporter of EU membership - made.
As for the letter...it won't have any influence in Europe. They will sit there and say 'what suits us in Europe, we have not got to consider British self-interest any more."
BBC News Channel
Speaking in Brussels, Danish politician Jeppe Kofod says the UK leaving the EU is like "losing a sibling", with Denmark having joined the bloc at the same time.
"It's not a day for joy - not for the UK, not for the EU, Denmark or anyone else," he adds.
In her interview with Andrew Neil, the prime minister said the UK would get the same benefits on trade outside the EU as inside: “It will be a different relationship, but I think it can have the same benefits in terms of that free access to trade.”
That sounds quite similar to what Brexit Secretary David Davis told the House of Commons on 24 January – that the government was aiming for a trade and customs arrangement with the “exact same benefits” as we currently have.
The EU’s chief Brexit negotiator, Michael Barnier, seems to disagree: he told a committee of the EuropeanParliament last week that by choosing to leave the single market and the Customs Union, the UK would “find itself in a less favourable situation than that of a member state”.
The full interview with Theresa May will be shown on BBC1 at 7pm.