British Prime Minister Liz Truss is facing an open revolt against her leadership as an increasing number of Conservative Party MPs call for her to resign amid mounting chaos at the heart of the UK government, with all eyes now on former chancellor Rishi Sunak to be parachuted in to take charge.

Sir Graham Brady, the senior-most Tory backbencher as the chair of the 1922 Committee, on Thursday met with her for an unscheduled meeting at Downing Street as at least 13 Tory MPs openly called for Truss to go.

Under the current rules, Truss technically cannot face a leadership challenge for at least 12 months but there are growing murmurs of either a swift change of rules or an ultimatum to her that she no longer has the support of her colleagues.

Sunak, who lost out to Truss' now failed tax-cutting agenda in the leadership race last month, is seen as a key contender to step up to the post. But the picture remains extremely uncertain due to deep infighting within Tory ranks. Loyalists of former Prime Minister Boris Johnson believe the party should bring him back, given his solid electoral mandate from the 2019 general election. However, Truss' current troubles are themselves reminiscent of how Johnson was dragged out of office and forced to resign in early July amid an open revolt by a growing number of his MPs and ministers.

The latest turmoil comes a day after Suella Braverman's explosive exit from the Cabinet after admitting a breach of the ministerial code by discussing government policy in private emails and a scathing parting attack on her boss.

Not only have we broken key pledges that were promised to our voters, but I have had serious concerns about this government's commitment to honouring manifesto commitments, such as reducing overall migration numbers and stopping illegal migration, particularly the dangerous small boat crossings, reads the Indian-origin former Home Secretary's resignation letter.

Her exit came over what experts believe was a relatively low-level ministerial breach but reflects more serious differences between Braverman and Truss over the country's immigration policy.

The Prime Minister attempted to move on from the latest crisis by swiftly appointing Grant Shapps as the new Home Secretary. But coming just days after she sacked Kwasi Kwarteng as chancellor and brought in Jeremy Hunt who has since reversed all of her economic agenda, the latest Cabinet upheaval is widely expected to only speed up Truss' exit from 10 Downing Street.

To make matters even worse, the Speaker of the House of Commons has ordered an investigation into reports of bullying and manhandling of some Tory MPs being made to vote with the government on an Opposition motion on Wednesday night.

Confusion erupted after Labour tabled a vote on whether MPs should get a say on the government's fracking plans to drill for gas. Conservative MPs were initially told the vote would be treated as a test of loyalty to the government, a so-called motion of confidence, and if they did not oppose the Opposition Labour motion they could face disciplinary action from the parliamentary party. Chaotic scenes were caught on camera in the voting lobby of the Commons as whips tried to get Tory MPs to oppose the Labour motion. There were reports of further resignations from Truss' top team, which were later withdrawn.

The Labour Leader, Sir Keir Starmer, has renewed his call for a general election as the only way out of the pathetic squabbles within the governing party.

All the failures of the past 12 years have now come to the boil, he said at an event in Brighton, with reference to the Tory-led government's term in office.