Boris Johnson wins race to be Britain's next leader

7:05 a.m. ET, July 23, 2019

BREAKING: Boris Johnson has won the Conservative party leadership race and will be the next prime minister

Boris Johnson has defeated Jeremy Hunt in the race to be the Conservative party leader and will be Britain's next prime minister.

The frontrunner will now make his first speech as Conservative leader, before taking over as PM on Wednesday.

7:01 a.m. ET, July 23, 2019

HAPPENING NOW: New Conservative leader is about to be announced

The stage is set, and the leader of the Conservative party -- and therefore prime minister --is about to be announced.

Follow all the updates here.

6:52 a.m. ET, July 23, 2019

Johnson yet to arrive at event hall

The event inside the Queen Elizabeth II Centre is running slightly behind schedule. Muse's anthem "Uprising" is playing over the speakers, but the Tory members and politicians in attendance seem unmoved.

Still no sign of Boris Johnson -- he is known to arrive fashionably late to events -- but Jeremy Hunt has already entered the hall.

6:25 a.m. ET, July 23, 2019

Education minister quits ahead of announcement

Another minister has resigned from the post ahead of Boris Johnson's expected confirmation as the new Conservative party leader.

Anne Milton, a minister in the department for education, warned of her "grave concerns" about a no-deal Brexit -- a scenario which Johnson says he is prepared to pursue.

"I have always believed that our departure from the European Union should be centered around future cooperation, and I had sincerely hoped we would have been able to leave the EU in March with a deal in place," she wrote. "I have grave concerns about leaving the EU without a deal, and so I feel it is time for me to return to the backbenches."

It's worth noting, of course, that a new prime minister usually sacks most of their predecessor's ministers after taking power -- and Johnson has indicated he wants to stack his Cabinet with hardline Brexiteers.

But expect a subplot of the day's events to be a wave of similar resignations, as the Conservative Party's two Brexit factions crystallize during Johnson's first days in charge.

6:54 a.m. ET, July 23, 2019

Anti-Johnson protesters gather near parliament

TOLGA AKMEN/AFP/Getty Images
TOLGA AKMEN/AFP/Getty Images

Boris Johnson isn't prime minister yet, but protesters are already gathering in Westminster to make clear their opposition to Britain's presumptive leader.

A small handful of anti-Johnson and anti-Brexit demonstraters are waving placards and chanting outside parliament as they await the results of the leadership contest in the next hour.

Meanwhile, Johnson's family members have arrived at the Queen Elizabeth II Center to watch the announcement.

TOLGA AKMEN/AFP/Getty Images
TOLGA AKMEN/AFP/Getty Images

5:50 a.m. ET, July 23, 2019

One hour until Britain's next PM is announced

Guests will soon start filing into the Queen Elizabeth II Centre in Westminster, central London, where the winner of the contest to replace outgoing Prime Minister Theresa May will be announced.

The result is due to be confirmed just after 11.40 a.m. (6:40 a.m ET) and the victor will make a speech immediately afterwards.

5:31 a.m. ET, July 23, 2019

Not everyone is gripped by Tuesday's contest

As reporters wait eagerly outside Downing Street, one observers seems disinterested in the historic events unfolding around him.

Larry the Cat, the prime minister's official pet, has taken up residence in the sunshine outside the famous door -- as journalists on site were quick to share.

Larry will soon have a new boss, but he won't be moving house -- as a civil servant, rather than a political appointee, the government's chief mouser will remain in his post whoever takes over as leader later on Tuesday.

Last month, Larry caused a geopolitical standoff of dramatic proportions when he sat underneath President Donald Trump's limousine, apparently undeterred by the Secret Service.

4:44 a.m. ET, July 23, 2019

Theresa May hosting final cabinet meeting

 Luke Dray/Getty Images
 Luke Dray/Getty Images

It's easy to forget, but Theresa May is still Britain's prime minister.

She held farewell drinks on Monday, and is holding her final cabinet meeting on Tuesday morning, as she wraps up her duties in the post. A number of ministers have been seen arriving at Downing Street, which is flooded with members of the press.

Jeremy Hunt was among those heading inside -- as foreign secretary, and with tensions with Iran escalating over the past few weeks, he still has plenty on his plate. But once the meeting has concluded, he'll be heading to watch the announcement of whether he -- or Boris Johnson -- will be the country's next prime minister. If Johnson triumphs, Hunt could find himself out of his ministerial position by the end of the week.

4:22 a.m. ET, July 23, 2019

Johnson could face a Tory mutiny within hours

NIKLAS HALLE'N/AFP/Getty Images
NIKLAS HALLE'N/AFP/Getty Images

If Boris Johnson is hoping for a honeymoon period should he becomes prime minister, he may have to think again.

Johnson would inherit Theresa May's perilously thin working majority in parliament, which currently stands at just two lawmakers. That small margin for error goes some way to explaining why May was unable to get a Brexit deal over the line -- and makes her gravity-defying three-year tenure in Downing Street seem rather impressive.

But Johnson could face even more bad news in the hours after he is announced as party leader. His hardline posturing on Brexit has excited those on the right wing of the Conservative party, but it's dismayed many moderates who fear a no-deal crash out of the EU. And it's led some senior figures to warn that they won't be signing up to his agenda.

The current chancellor Philip Hammond said on Sunday that if Johnson wins, he'll be resigning to Theresa May before she officially resigns on Wednesday, and has made clear he'll be opposing any attempt by Johnson to pursue a no-deal Brexit.

International development secretary Rory Stewart, who made a high-profile but unsuccessful bid to challenge Johnson for the role, has also reiterated that he won't be helping a hardline Johnson strategy. And longtime Johnson critic Alan Duncan has already quit his post in the Foreign Office this week.

Want even more bad news? A by-election in Brecon is set for August 1, in which the Tories are expected to lose another seat -- so Johnson's majority could be cut to one seat within his first fortnight in the post.

What does this all mean? Well, it's virtually inevitable that Johnson's tenure as prime minister will be rocky and eventful.