The Prime Minister's statement was due to begin at 11.15am - but the eager Tory leader came out early to announce the snap poll. Yougov have a list.
Labour leader Jeremy Corbyn has welcomed the decision "to give the British people the chance to vote for a government that will put the interests of the majority first".
This is despite the Labour party being 21 points behind in polls published over the weekend.
Article 50 is being triggered today. Which means the UK will leave the EU by 2019
The Prime Minister has signed the six-page letter that kicks off two years of negotiations between the UK and the other 27 member countries which will determine what relationship they have after it leaves in 2019.
The mechanism is due to be invoked at 12.30pm UK time when the document is hand-delivered to Mr Tusk, the President of the European Council, and Ms May will then make a formal statement to MPs confirming the start of the process.
The full text of the letter will then be released and copies will be sent to all 27 member states.
The purpose of the Great Repeal Bill is sensible enough – but the devil is in the detail. It seems almost certain that, in order to process thousands of pieces of legislation, the government will try to give itself unparalleled power.
Under 'Henry VIII clauses' – named after statutes passed in the English Reformation, and set after Henry's death – government ministers would get powers to repeal legislation without approval of parliament. Given the quantity of EU law, this could easily include rights, protections and standards that all of us take for granted in our everyday lives.
Today campaign groups "Another Europe is Possible and Global Justice" Now are calling on MPs to wake up to threats to our rights.
They are calling on the Government to release clear detailed bills as soon as possible, to guarantee reasonable time for public consultation and parliamentary debate, to reduce Henry VIII powers and impose strict sunset clauses when extraordinary powers cease, and to guarantee that human rights or equalities legislation will be not be reduced and to be delegated by parliament.
I want us to employ the power of government as a force for good to transform the way we deal with mental health problems. pic.twitter.com/xK421SOhcf— Theresa May (@theresa_may) January 9, 2017
Prime Minister Theresa May has also reacted, saying: “I would like to congratulate Donald Trump on being elected the next President of the United States, following a hard-fought campaign.
“Britain and the United States have an enduring and special relationship based on the values of freedom, democracy and enterprise.
“We are, and will remain, strong and close partners on trade, security and defence.
“I look forward to working with President-elect Donald Trump, building on these ties to ensure the security and prosperity of our nations in the years ahead."
Theresa May will not formally begin the Brexit Article 50 process until the end of March 2017
Theresa May became the second female PM in Britain’s history when she took office on 13th July 2016. She replaced David Cameron as leader of the Conservative party.
May: We must embrace new Brexit opportunities and become an "independent Britain, forging our own way in the world". pic.twitter.com/El7hVqBRWc— LEAVE.EU (@LeaveEUOfficial) September 4, 2016
August 31 - Theresa may rules out second eu referendum as she insists 'brexit means brexit' Mrs May said "quite a lot of work" had already been done over the summer on preparing the way for exit negotiations under Article 50 of the EU treaties.
She told colleagues it was "a very significant moment for the country, as we look ahead to the next steps that we need to take".
The PM said: "We have the opportunity to forge a new positive role for the UK in the world, to make sure that we are that Government and country that works for everyone - that everyone can share in the country's prosperity.
"So there are challenges ahead but it's an important and significant moment for us and I think we have real opportunities to develop the United Kingdom and ensure that it does work for everyone in the UK."
Despite pressure from Leave supporters for a swift departure from the EU, Mrs May has already made clear she will wait at least until the end of this year before triggering the two-year process by invoking Article 50.
July 27th - During talks with Italian counterpart Matteo Renzi, the UK PM suggested she favoured bespoke arrangements rather than replicating those used by others.
"I think we should develop the model that suits the UK and EU," she said.
Mr Renzi said the EU vote was sad but he hoped "some good would come of it".
The prime minister said Brexit meant a "new chapter" in Anglo-Italian links but she said she hoped the current £24bn annual two-way trade could be boosted and the nations would continue to co-operate within Nato, G7 and the G20 to face the "complex and global challenges" posed by terrorism and mass migration.
July 26th - Theresa May to hold Brexit talks with Enda Kenny
The TUC has said the outline of an "all-Ireland" economic and security agreement is needed before the UK can press ahead with EU exit negotiations.
Yesterday Mrs May said there would be no “return to the borders of the past” in Ireland once the UK has completed the process of formally leaving the bloc.
July 19th - The new prime minister reassigned Watford MP Richard Harrington from under secretary of state for Syrian refugees to become the junior minister responsible for pensions.
Born in Yorkshire in 1957, former property developer and hotelier Mr Harrington was elected to Parliament in the Hertfordshire constituency six years ago. This is Money
Priti Patel International Development
UK-born to Ugandan parents who ran a newsagents’ chain, 44-year-old attended Watford Grammar and Keele University. DailyMail
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