Christopher Furlong / Getty Images At 12:15pm on Monday, after just minutes of warning to journalists, energy minister Andrea Leadsom gave a short statement announcing she was withdrawing from the Conservative leadership race, endorsing her rival, home secretary Theresa May, and calling an end to the contest nine weeks early.Here's what happens now. Is May prime minister now? Dan Kitwood / Getty Images Not yet.The first thing that needed to happen was for May to become the official leader of the Conservative party. This requires the formal agreement of the party's board and a senior group of its MPs (the 1922 Committee's executive board).This is largely a formality, but took several hours on Monday afternoon. The chairman of the 1922 Committee told journalists "we have no need to re-run the [leadership] election" minutes after Leadsom's resignationHowever, it wasn't until 5pm when he appeared and gave a short statement announcing May was now Tory leader "with immediate effect".Brexit supporters Michael Gove and Boris Johnson – both of whom have previously been seen as leadership rivals for May – both endorsed May for leader within minutes of Leadsom's withdrawal. So will May be prime minister after *that*, then? Wpa Pool / Getty Images Still not quite. The prime minister is appointed by the Queen once someone has demonstrated they can command a majority of MPs in the House of Commons. May's official confirmation as Conservative party leader would be the demonstration of this.However, Cameron would have to present his resignation to the Queen, and May would need to meet with the Queen to secure her appointment.This can't happen immediately as the Queen is not in London. She's presently believed to be in Norfolk (at Sandringham) and is not expected back in London until later this week.Speaking on Monday afternoon, Cameron said the transition will happen on Wednesday. Cameron will chair his last cabinet meeting on Tuesday, take Prime Minister's Questions on Wednesday, and then resign that afternoon.This means May will be prime minister by Wednesday evening. What happens to David Cameron now? Wpa Pool / Getty Images Unlike the USA, the UK doesn't have any kind of transition period, or PM-elect, so Cameron is likely to end his tenure as prime minister this week – about two months earlier than he expected. In practical terms, it's unlikely he'd be forced to move his family out of the residential flat in 10 Downing Street the same day he resigns, but PMs generally move out very quickly.This provides a slight practical problem for Cameron: His home in Notting Hill – just around the corner from Michael Gove – is believed to still be occupied by tenants. This may require the PM to stay in his constituency home in Witney, near Oxford, for a few weeks.Cameron has said he does not intend to resign as an MP when he steps down as prime minister. How is it possible to become prime minister with only 199 MPs voting for you? Christopher Furlong / Getty Images The UK works under a parliamentary system, not a presidential one. This means that during a general election, we're all electing a local MP from a particular party. The party – or coalition of parties – with a majority of the House of Commons (326 or more out of 650 MPs) then forms the government, and the head of that party becomes the prime minister.The Conservatives still have a majority of MPs and are under no legal obligation to have an election until 2020, and so May is able to succeed Cameron as PM without going to the country.When Gordon Brown succeeded Tony Blair in 2007, he didn't require a vote of Labour members, and he didn't call a general election until 2010. Will there be a general election? Adrian Dennis / AFP / Getty Images There's no reason to expect an instant general election: Legally, May does not have to call one until 2020, and during the leadership contest she pledged not to call a snap election.That said, an early election remains possible. The Conservative party has only a small majority in the House of Commons, and May has run on a different manifesto to Cameron's – it's not yet clear whether she would have strong Conservative support for all of her policies.May might also be tempted to capitalise on the chaos within the Labour party to seize her own mandate, especially ahead of long and difficult EU negotiations and probable economic turmoil. A sensible window might be to call an election in the autumn, which would still leave time to trigger Article 50 (if May so wished) by the end of the year. Can May call an early election if she wants to? Jeff J Mitchell / Getty Images The last government introduced the idea of five-year "fixed-term parliaments" in the UK. These nominally fix the date of the next general election – in this instance, to May 2020. To have an earlier election requires a vote of two-thirds of MPs, or to repeal the Fixed Term Parliament Act (which would require votes in the Commons and the Lords).In practice, this probably wouldn't prove a major barrier. Speaking on Monday afternoon, Labour election coordinator Jon Trickett called for an early election.“It is crucial, given the instability caused by the Brexit vote, that the country has a democratically elected prime minister," he said. "I am now putting the whole of the party on a General Election footing. It is time for the Labour Party to unite and ensure the millions of people in the country left behind by the Tories' failed economic policies, have the opportunity to elect a Labour government." Given Labour have publicly called for a general election, it would be extremely difficult for them to then try to oppose one in parliament. Hang on, aren't Labour having a leadership contest of their own? Jack Taylor / Getty Images Yes. Yes, they are.After weeks of rumblings, resignations, accusations, and counter-accusations, and a no-confidence vote, former shadow business secretary and first secretary of state Angela Eagle officially launched her leadership bid at noon on Monday – only to see journalists file out of the room as Leadsom announced her withdrawal from the Conservative leadership race.However, within two hours, Labour's general secretary confirmed he had received the 50 nominations from MPs required to launch a leadership challenge, meaning that under the party's rules, a contest is formally underway.Labour party rules require that a contest, once launched, runs until the party conference – this year at the end of September – when the votes are counted and the new leader is formally announced.Labour's national executive committee is expected to rule on Tuesday as to whether Jeremy Corbyn, the current leader, will need to get nominations from MPs in order to appear on the ballot. Corbyn's supporters say that as current leader, he should automatically appear on the ballot as challenged, because he's the incumbent. His opponents say the rules imply he needs to seek nominations. Both sides have legal advice supporting their position. Corbyn is expected to struggle to gather 50 nominations, should he need them.The party's rules do not appear to include any official mechanisms to cancel or suspend a leadership election in the event of a general election. Does this affect when the UK might trigger Article 50? Christopher Furlong / Getty Images Article 50 is the official starting trigger on when the UK begins the formal process of withdrawing from the EU.May signalled during the leadership context that she intends to honour the EU referendum and exit the EU – and that she wants more control of the UK's borders, so does not intend to enter the single market.The home secretary said during the leadership contest, however, that she would not trigger Article 50 by the end of 2016. EU leaders are understood to be keen for the UK, if it is leaving, to get the process underway.German chancellor Angela Merkel was willing to wait until the end of 2016 for Article 50 to be triggered, but this was predicated on there being no new Conservative leader until September. It's unclear at this time whether she will push for an earlier trigger of the process. What happens to the cabinet? Christopher Furlong / Getty Images The cabinet – the senior ministers responsible for actually running the country – are appointed by the prime minister, and so when May enters Number 10, she will immediately be able to reshuffle the key positions.May has already announced she will introduce a senior minister in charge of implementing Brexit, but will probably make wider cabinet changes. It's seen as unlikely that George Osborne could remain chancellor under May, while a close eye will also be kept on what roles May – a Remain supporter, albeit not a prominent one – gives to key pro-Brexit figures such as Johnson, Gove, and Leadsom. Finally: What happens to Larry, the Number 10 cat? Oli Scarff / Getty Images Larry, Number 10's cat, is a pet of the civil servants working in the office rather than the personal pet of the prime minister and his family. His food is bought out of a kitty funded voluntarily by the people working in Downing Street.As such, BuzzFeed News understands Larry is not expected to move out of Number 10 with the Camerons. Larry moved into Number 10 in 2011, meaning he has now outlasted the leaders of every major political party – the Conservatives, Labour, the Liberal Democrats, UKIP, the Greens, the SNP, and Plaid Cymru.On Wednesday night, a spokesman for Theresa May confirmed to The Sun that Larry would stay on as chief mouser to the Cabinet Office."Larry can sleep easy," he said.This makes Larry the first appointment for Theresa May's administration.