- 67 updates
It's been 37 years since Margaret Thatcher walked in to 10 Downing Street, but Theresa May is set to make her own mark on history.
Mrs May looks set to appoint a record number of women in her Cabinet later this week.
ITV News correspondent Juliet Bremner reports:
Theresa May moved into Number 10 on a momentous day in British politics, which saw David Cameron and his family leave Downing Street for the final time after six years in office.
Mrs May didn't delay getting straight to work, making key appointments in her new cabinet including Boris Johnson as Foreign Secretary.
ITV News' Political Editor Robert Peston reports:
Labour leader Jeremy Corbyn has congratulated Theresa May on becoming prime minister, but called on the new government to "abandon the destructive austerity policies which have damaged our economy and undermined living standards for most people".
The embattled Labour leader said in a statement: "I welcome Theresa May's acknowledgement that, after six years of Tory government in which she was a senior minister, the economy is not working for working people."
He added that "Labour will hold her government to account and make the case for a complete change of economic direction" and that the EU referendum result shows many in Britain feel left behind by globalisation and "it is essential that the new government recognises that and acts to ensure future generations have the chance to fulfil their potential".
"Labour is clear that democratic legitimacy for Theresa May's government can only come from a general election", the statement ends.
French President Francois Hollande has urged Theresa May to begin Brexit negotiations as quickly as possible, his office said after a phone call between the two leaders on Wednesday.
In a statement, the President's office said: "They agreed to actively develop the bilateral relationship that warmly unites France and Britain in all fields.
"The president repeated his desire that negotiations for Britain's exit from the European Union should be launched as quickly as possible."
The prime ministers of Canada and Belgium have joined leaders from around the world in congratulating Theresa May on becoming prime minister.
Justin Trudeau, the Canadian prime minister, issued a statement congratulating Mrs May and paying tribute to David Cameron.
Meanwhile, the prime minister of Belgium, Charles Michel, took to Twitter to congratulate Mrs May, saying he hopes the UK will be a "close partner" of Belgium.
Russian President Vladimir Putin has thanked David Cameron for his time as UK prime minister, and congratulated Theresa May on replacing him.
Theresa May has pledged to fight key social injustices, including women earning less than men and black people being "treated more harshly" than white people by the criminal justice system.
Speaking in Downing Street in her first public address since becoming prime minister, Mrs May said the full title of her party - the Conservative and Unionist Party - is a reflection of the "precious, precious bond" between the nations of the United Kingdom but also the union between "every one of us - whoever we are and wherever we're from".
"That means fighting against the burning injustice that if you're born poor you will die on average nine years earlier than others," she said.
"If you're black you are treated more harshly by the criminal justice system than if you're white. If you're a white working class boy you're less likely than anybody else in Britain to go to university.
"If you're at a state school you're less likely to reach the top professions than if you're educated privately. If you're a woman you will earn less than a man.
"If you suffer from mental health problems, there's not enough help to hand. If you're young you will find it harder than ever before to own your own home.
"But the mission to make Britain a country that works for everyone means more than fighting these injustices. If you're from an ordinary working class family, life is much harder than many people in Westminster realise."
Latest ITV News reports
The appointment of Theresa May means there have been 13 UK prime ministers to serve Queen Elizabeth II.
From David Cameron's last Prime Minister's Questions, to Theresa May meeting The Queen, here is how the day unfolded in pictures.