Boris Johnson has officially been appointed Prime Minister after meeting Queen Elizabeth II at Buckingham Palace.
Mr Johnson accepted the Queen’s invitation to form a new Government, arriving at the palace minutes after Theresa May resigned as PM.
In his first speech outside Number 10, he promised in no uncertain terms to deliver Brexit by 31 October.
“The people who bet against Britain are going to lose their shirts because we are going to restore trust in our democracy,” he said.
“And we are going to fulfil the repeated promises of Parliament to the people and come out of the EU on October 31, no ifs or buts.
“And we will do a new deal, a better deal that will maximise the opportunities of Brexit while allowing us to develop a new and exciting partnership with the rest of Europe based on free trade and mutual support.
“I have every confidence that in 99 days time we will have cracked it.
The new PM made a new promise to ‘fix the crisis in social care once and for all’ saying he has already prepared a plan to do so.
He also repeated his capaign pledge to get an additional 20,000 more police officers on the streets,
Mr Johnson’s girlfriend Carrie Symonds was present at Downing Street for his maiden speech, despite rumours she would stay away to avoid media focus on their relationship.
It is not yet clear wether Ms Symonds will move into Number 10 with her partner.
Mr Johnson was confirmed as the new leader of the Tory party yesterday after defeating rival Jeremy Hunt in a ballot of Conservative Party members with 66% of the vote.
Mrs May gave her final PMQs earlier where she told Labour leader Jeremy Corby that he should quit his post as his “time was up”.
She later gave a short farewell speech outside Number 10, saying she wanted a Brexit "that works for the whole United Kingdom".
Mrs May also gave a supportive message to Mr Johnson, adding: "I repeat my warm congratulations to Boris on winning the Conservative leadership election.
"I wish him and the government he will lead every good fortune in the months and years ahead.
"Their successes will be our country's successes and I hope that they will be many."
Mr Johnson’s first move will be to appoint a Cabinet, after his team promised he would form a Government that ‘reflects modern Britain’.
Chancellor Philip Hammond, Justice Secretary David Gauke and International Development Secretary Rory Stewart all resigned from their posts just hours before Mr Johnson became PM, while Deputy PM David Lidington also handed in his notice.
They will now fight a no-deal Brexit from the backbenches, giving Mr Johnson an early headache in his reign.
Eurosceptic Priti Patel is expected to be named Home Secretary in Mr Johnson’s Cabinet, while Vote Leave campaign mastermind Dominic Cummings is set to be named senior adviser.
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Uncertainty surrounds the future of Mr Johnson's defeated leadership rival Jeremy Hunt after he reportedly turned down a demotion from Foreign Secretary to Defence Secretary.
Mr Johnson’s allies said he was determined to create a cabinet with a record number of ethnic minority ministers and more women attending in their own right.
It is likely to mean a promotion for the Indian-born Employment Minister Alok Sharma, who is expected to take his place around the top table.
Mr Johnson has said he wants ministers who are prepared if necessary to leave the EU without a deal with Brussels.
Among the more junior ministerial ranks, promotions are expected for Local Government Minister Rishi Sunak, Cabinet Office Minister Oliver Dowden and Treasury Minister Robert Jenrick.