Shortly before four o’clock on Wednesday afternoon, Boris Johnson gave his first address as Britain’s seventy-seventh Prime Minister. Like the seventy-sixth, Theresa May, Johnson has entered Downing Street at a time of acute national distress, elected by the members of the Conservative Party rather than by the population as a whole. But that is where the similarities end. In the summer of 2016, May was chosen by her party to tackle the enormous implications of Britain’s decision to leave the European Union because she was seen as credible, selfless, and pragmatic—and as having a shot at uniting the country. May failed.

Three years later, the party has gone for a very different solution to many of the same problems. Johnson, who is fifty-five, shares very few of May’s positive qualities. No one would call him honest. But Johnson does not share some of May’s deficiencies, either. May was awkward, sometimes touchingly so, and unable to convey a positive, healing vision of what post-Brexit Britain might look like. Johnson is nothing except oomph. “After three years of unfounded self-doubt, it is time to change the record,” he said in the sunshine, outside the door of No. 10 Downing Street, above the faint sound of protesters at the gates. “The doubters, the doomsters, the gloomsters are going to get it wrong.”

What will happen next is anybody’s guess. Britain is due to leave the E.U. on October 31st. After almost two years of talks with Brussels, May was unable to steer her Brexit deal through Parliament, failing on three occasions. With a little more bounce in his step and a few references to the Apollo program, Johnson has promised to negotiate an entirely new agreement in the next ninety-nine days. “We will do a new deal, a better deal,” he said on taking office.

Everyone knows that this will be impossible to achieve by conventional means. None of the facts, or the parliamentary math, that undid May have changed. In his speech, Johnson rushed through a line about the “anti-democratic backstop”—the issue of the Irish border—that ultimately scuppered May’s deal. In the House of Commons, Johnson will have a working majority of two. It seems that his plan is either to be crazy enough to end Britain’s forty-six-year political and economic relationship with its nearest neighbors with no deal whatsoever, or to convince them that he might be. Earlier in the day, Johnson hired Dominic Cummings, the maverick director of the Vote Leave campaign, to join his administration, a clear sign that he might be thinking the unthinkable. He devoted a good portion of his speech to the “remote possibility” of preparing the country for no deal. “To all those who say we cannot be ready, I say, ‘Do not underestimate this country,’ ” Johnson said. “Do not underestimate our powers of organization and our determination.”

After three years of May’s careful, modulated addresses, Johnson waved his arms in a purposeful fashion. “Let’s get going now,” he said, rattling off references to the nation’s expertise in gene therapy and blight-resistant crops, along with the country’s famous love of animals. Within three hours, more than half of May’s cabinet had either resigned or been sacked, including Britain’s Chancellor and Foreign Secretary, and replaced with Johnson supporters. He has the stage now.

Read More Sam Knight’s profile of Boris Johnson from the June 24, 2019, issue of the magazine.

It is a weird fact of political life that almost all politicians—even the most minor and mediocre ones—secretly believe that they will become President or Prime Minister one day. Even so, Johnson has dreamed more strongly, and more incessantly, of this day than most. This is the man who, as a boy, wanted to become “world king,” and whose ambition has been so obvious that it rubbed off on everybody else. Since 2001, when Johnson first became a Member of Parliament—he was editing The Spectator, a right-wing political magazine, on the side—the outrageous possibility that he would become Prime Minister one day has been talked about so often, and with such happy disbelief, that it is hard to identify the moment when incredulity turned into expectation. Even when people have despised Johnson, his actions—whether as the mayor of London, campaigning for Brexit, writing a biography of Churchill, or messing about as Foreign Secretary—have always been framed as part of his ambition to rule the country. His political career has not consisted of doing politics in any ordinary sense. It has all been preparation. Johnson himself has spoken of “this cursus honorum, this ladder of things” that he has felt compelled to climb throughout his life. Now he is at the top, with nowhere else to go.

It is hard to predict how Johnson will respond to finally getting the thing that he wants. (In 2016, when he was the overwhelming early favorite to succeed David Cameron, he collapsed in prevarication and self-doubt.) But there are several things that we can safely say. The first is that, until now, Johnson has never been a very effective politician. In his most important executive role, as the mayor of London, Johnson did fine. Neither more nor less. He had no major policy agenda and, beyond a few vanity projects, he left the city basically untouched. Johnson is much more interested in having power than in doing anything with it. As Britain’s Foreign Secretary, between 2016 and 2018, he was in a position to work on the momentous job of leaving the E.U., a cause that he had championed for much of his working life. But he simply shambled about, making mistakes. “Cleaning after him was quite a full-time activity,” Alan Duncan, a junior minister who worked for Johnson, said last month. (Duncan has resigned, rather than serve in a Johnson government.)

If there is any consolation, it is that Johnson is not an extremist of any kind. By temperament and by upbringing, Johnson is a metropolitan liberal: pro-choice, pro-immigration, tolerant of diversity, educated about the world, and prepared to accept the consensus on climate change. The problem is that he is also so unserious and so unprincipled that it is impossible to know if he would maintain any of those positions under meaningful duress. It is wrong to compare Johnson to Donald Trump—they are very different. But they share a quality of constant distraction, a permanent, enervating uncertainty about what they will get up to next. One of Johnson’s favorite political gestures, which he credits to the Australian political strategist Lynton Crosby, who has overseen much of his rise to power, is “throwing a dead cat on the dining-room table”—saying or doing something so remarkable that it shifts the conversation entirely. Johnson was notably cautious and buttoned-up during his leadership campaign, but that did not stop him from throwing dead cats. He waved a kipper during a harangue against what he called onerous E.U. regulations, though the rule governing the kipper was actually British. He distracted the media, which was chasing every detail of a late-night altercation between Johnson and his partner, Carrie Symonds, during which the police were called, by promising to leave the E.U., “do or die,” on October 31st. And he declined to support Britain’s Ambassador to the United States, Kim Darroch, by all accounts a skilled and decent diplomat, because he was afraid of displeasing the Trump Administration. Johnson’s tenure is going to be exhausting.