Polling expert Professor Sir John Curtice says we should remember that Boris Johnson still faces a parliamentary investigation by the privileges committee into whether he deliberately misled the Commons over Downing Street parties.

He says therefore Tory MPs may be “very wary” of having Johnson back in office "and then finding themselves embroiled in exactly the same arguments about his probity from which they thought they had escaped".

He thinks Rishi Sunak, Penny Mordaunt and Suella Braverman are more realistic prospects to become the next PM.

But Curtice has this advice for whoever wins: "Enjoy the next 18 months to two years because that is probably the length of your tenure.”

He says parties in government who preside over a fiscal crisis have nearly always struggled at the ballot box at the subsequent election.

Chris Mason
Political editor

As speculation immediately begins that Boris Johnson will stand again in the contest to be Conservative leader, those around him are not knocking these stories down.

A source tells me he is "not saying anything either way" at the moment.

Ione Wells
Political correspondent

I've already had several messages today from MPs and aides who backed Rishi Sunak in the last Tory leadership race who are saying they are now #ReadyforRishi again.

He's been quiet publicly so far, but certainly his allies feel that his economic argument during the summer has now been "proved right' by the market reaction to Liz Truss's mini-budget, and that that may work in his favour should he choose to run.

Liz Truss had barely stepped away from the lectern outside Downing Street when thoughts turned to who would succeed her as Conservative Party leader.

It's being reported that Boris Johnson is expected to stand but we're not yet able to confirm this. He is currently on holiday in the Caribbean.

There's been no soundings yet from the contender who came closest to entering No 10 in the last Tory leadership race, former Chancellor Rishi Sunak, but reports suggest he's ready to stand.

But Chancellor Jeremy Hunt was quick to rule himself out - which some say could bolster a Sunak ticket.

Penny Mordaunt who, following Truss's resignation announcement, said she would "keep calm and carry on", came third in the summer leadership contest. She is a likely leadership contender, although she hasn't officially said so yet.

Other names being floated are Defence Secretary Ben Wallace, International Trade Secretary Kemi Badenoch, Foreign Secretary James Cleverly and recently-resigned Home Secretary Suella Braverman.

While none of the four have stated their leadership ambitions this afternoon, it's reported that allies of both Badenoch and Braverman say they are intent on running.

Meanwhile, there have been unconfirmed reports that veteran Tory Michael Gove, one of Truss's fiercest critics, and Tom Tugendhat - who have both run in previous contests - have ruled out standing this time.

Image source, Daily Star

Last Friday, the Daily Star newspaper set up a live feed showing a wig-wearing lettuce next to a photo of Liz Truss, asking readers whether the salad vegetable or the prime minister would last longer.

It emerges the iceberg lettuce has won.

More than 12,000 Twitter users were watching the feed ahead of Liz Truss's speech - viewer numbers then quickly shot up to 21,000 as she announced she was resigning.

The lettuce is now surrounded by other vegetables with googly eyes and several discarded bottles of gin and champagne. Disco music and strobe lights complete the scene.

The frame carrying Truss's photo has been flipped down.

Scotland's First Minister Nicola Sturgeon has called recent events an "utter shambles" and said a general election is a "democratic imperative".

Labour leader Sir Keir Starmer has repeated his call for a general election following news of Liz Truss's resignation.

But he says she has left a mess which is "doing huge damage to our economy and to the reputation of our country."

He says "we can't have another experiment at the top of the Tory Party" and says Labour would offer a stable government.

Image source, Getty Images

Former Prime Minister Boris Johnson - who left office just six weeks ago - could stand in the upcoming Conservative leadership contest to replace Liz Truss, according to reports.

Both the Times and the Daily Telegraph are reporting that Johnson - who was forced to resign as Conservative leader in July following a string of scandals - is preparing to run again for the top job.

Johnson believes it's a matter of "national interest", the Times reports, external.

The exact rules for the contest have not yet been revealed. Earlier, 1922 Committee chairman Sir Graham Brady suggested members - with whom Johnson remains highly popular - would be involved. But Brady also suggested it was possible Tory MPs might agree on a single candidate.

Over in Washington, White House Chief of Staff Ron Klain says the United States will have a close relationship with whoever replaces outgoing UK PM Liz Truss.

In an interview on MSNBC, he also said President Joe Biden would issue a statement later on Thursday.

Hard to imagine Tory MPs uniting behind one candidatepublished at 14:56 British Summer Time 20 October 2022

14:56 BST 20 October 2022

Nick Eardley
Chief political correspondent

Remarks made by 1922 Committee chairman Sir Graham Brady - that under current rules, the last two candidates from the leadership contest go to the membership unless there's only one left - suggest there is still a bit of wiggle room.

One of the wheezes that's been discussed in Parliament in the last few days is that MPs could set such a high threshold that only an MP with a lot of support would get there.

It's not certain what's going to happen, to be frank. This is an unprecedented situation.

We should have more details by the end of the day. Brady will be conscious of spelling out how the next leader will be chosen.

There are a lot of MPs who don't want this to go to the Conservative Party membership - they think a new leader needs to be chosen as quickly as possible.

The logistics of trying to consult the membership in only a week are hard to figure out - unless it was a quick online ballot. But even that would be a hard task.

As for MPs, if they're to end up choosing the next leader themselves, how can they coalesce around one person? It seems unlikely, impossible even.

So, we wait for more details on what exactly will happen.

Image source, Reut

Following Liz Truss's resignation, Mark Drakeford says that a complete lack of leadership is stopping actions being taken to deal with the challenges the UK is facing.

He also says that the people of the country are paying the price.

He continues: "Unfortunately, the deep and intractable divisions within the government means that any successor put forward will face the same set of challenges. A general election is now the only way to end this paralysis."

The pound rallied as financial markets reacted to the announcement that Prime Minister Liz Truss is stepping down after just six weeks in the job.

Sterling shot up to 1.13 US dollars before she made her speech as markets anticipated that Truss would go.

But it's since fallen back slightly. It was trading around 0.4% higher at 1.126 US dollars about 30 minutes after her statement.

Image source, .

Ione Wells
Political correspondent

Sir Graham Brady has confirmed that Tory party members will have a say in the new Conservative leadership race - if it comes down to two candidates.

If the MPs somehow united around one candidate, that may not happen, he suggested, saying: "If there is only one candidate, then there is only one candidate."

But this outcome seems unlikely given some of the factions within the party.

If members have a say again this could get complicated. Remember last time Rishi Sunak came top in the initial round of MP votes, but then the membership picked Liz Truss over him. The membership and Tory MPs are not always, to use a very overused phrase from the last few days, "in lockstep".

The big question on everyone's minds here is if anyone can win the support of both MPs and members.

We're just finding out a bit more about the rules of the leadership contest and we'll bring you more details shortly.

But from the minute Liz Truss walked away from the lectern, frenzied speculation over who could succeed her as Tory party leader and prime minister began.

Her former leadership rival Rishi Sunak is the bookmakers' favourite to take over in No 10, followed by Penny Mordaunt and Defence Secretary Ben Wallace.

Chancellor Jeremy Hunt has already ruled himself out of the race, while former PM Boris Johnson is fourth favourite to return to Downing Street.

Sir Graham Brady says he expects a leadership result by Friday next week.

The 1922 Committee chairman says he expects Tory members to be included in the leadership contest.

There had been speculation the rules of the contest could be changed to exclude members.

The chairman of the influential 1922 Committee of backbench Tory MPs Sir Graham Brady is making a statement outside Parliament.

It is anticipated he will set out the rules as to how the Tory Party will choose its next leader.

Labour's Keir Starmer, Ed Davey, the leader of the Lib Dems, and the SNP have all called for a general election to be called immediately.

Image source, Reuters

Some international reaction to bring you now to Liz Truss's resignation.

French President Emmanuel Macron said it was important the UK finds "stability as soon as possible".

Arriving at a European Union summit in Brussels he told reporters: "We want, above all else, stability

"On a personal level, I am always sad to see a colleague go."

Here's the full statement Liz Truss delivered outside Downing Street confirming her resignation as prime minister.

Chris Mason
Political editor

It's astonishing, just three and a half months ago I was standing in this very spot reporting on the resignation of the previous prime minister from the Conservative leadership.

Here we are just 100-odd days later and his successor, Liz Truss, performs that same walk and utters a very similar set of words.

If you thought yesterday was chaotic, the chaos is going to deepen. In the next few days another prime minister is going to emerge.

Conservative MPs hope they can dredge a name out of their ranks amongst themselves to avoid a contest among Conservative Party members. That would take several months in order to present yet another leader to the country.

That new prime minister - if they can find someone who can unite the party - and that is a massive if - will then face a huge challenge around legitimacy.

But we should remember, constitutionally, we live in a parliamentary democracy and if a new prime minister can command a majority in the House of Commons, they have the constitutional right to serve until the next general election legally has to happen.