Cameron resigned after Britons voted June 23 - against his advice - to leave the EU.
He found time to congratulate Wimbledon victor Andy Murray and other British players there, and rebuffed rumors that he does not like Downing St.'s resident cat, Larry - "I do!"
The 44-year-old Gujarat-origin MP was a significant pro-Brexit voice, who had recently thrown her support behind May as the ideal candidate to become the Prime Minister, likening her to her predecessor Margaret Thatcher - described as the Iron Lady of British politics.
"The Channel will not get any wider once we leave the European Union and that is the relationship that we should seek, that would be good for the United Kingdom".
May promised to fight for social justice in a speech that addressed "hard-working families" who have struggled during the years of instability since the 2008 financial crisis. He lost a vote of no confidence among Labor MPs by 172 votes to 40.
"When it comes to opportunity we won't entrench the advantages of the fortunate few".
Mr Cameron and his wife Samantha are keen curry fans and make a point of tasting local curry restaurants during the Conservative party conference season - whether in Birmingham, Manchester or Brighton.
After taking office, Mrs May, the home secretary, will set about naming her own frontbench team.
"The UK finally has a new prime minister", Gianni Pittella, the leader of the centre-left group in the European Parliament said in a statement as Theresa May took over the government. 'OUR ANGELA MERKEL' May, who has been interior minister for six years, is seen by her supporters as a safe pair of hands to steer the country through the disruptive Brexit process.
Today, in fact, the outgoing Prime Minister was dealing with the last bit of parliamentary drilling at the House of Commons as the movers drove in to 10 Downing Street.
While Mr Cameron tucked into the curry bought by their boss last night, the Prime Minister in-waiting spent her final evening before becoming Prime Minister having dinner with the Chief Rabbi.
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The leading Leave campaigner said it was right that the minister given responsibility for heading Brexit negotiations should be "somebody who was at the heart of the Leave campaign".
David Cameron has left 10 Downing St.to go to Buckingham Palace to tender his resignation as prime minister.
Graham Brady, head of the Conservative party committee in charge of the leadership contest, said there were still constitutional procedures to be observed before her appointment could be confirmed, but he aimed to make a confirmation announcement as soon as possible.
Her immediate challenge is to form a new cabinet, which can help heal the Conservative party's divisions following a bruising referendum campaign.
Hammond, the former foreign secretary, replaces George Osborne, who had held the job for six years.
She is also expected to meet Scottish First Minister Nicola Sturgeon in the coming days, with Sturgeon telling a press conference Wednesday that Brexit "does not apply to Scotland, as Scotland voted differently in the referendum".
Although May had backed remaining in the European Union, she has reassured "leave" supporters that "Brexit means Brexit, and we will make a success of it".
Not all believe her.
"I am therefore withdrawing from the leadership election and I wish Theresa May the very greatest success". "I think she's a cautious person, and the British political establishment needs to come to terms with this massive decision".
Although she favoured Britain remaining in Europe, May has repeatedly declared that "Brexit means Brexit" and that there can be no attempt to reverse the referendum outcome.