At 2.30 pm, a fresh group of 643 Members of Parliament were scheduled to assemble on the green benches to pick a Speaker, who will oversee the House of Commons and its internal debates.

Following the General Election last Thursday, Sir Keir obtained the keys to Number 10 Downing Street and was scheduled to make his first remarks at the despatch box as Prime Minister.

Prior to Wednesday, July 17, when Parliament holds its State Opening, the 643 members are required to take an oath promising to “be faithful and bear true allegiance to His Majesty King Charles, his heirs and successors, according to law”.

Sinn Fein which won seven seats across Northern Ireland, including two in Belfast, have a long-standing policy of abstentionism so do not take their seats in Westminster.

Before they elect a Speaker, Black Rod Sarah Clarke must summon MPs to the House of Lords.

She will cross through Central Lobby to fetch Father of the House Sir Edward Leigh, and walk him to the Lords, where a Royal Commission will be read directing MPs to choose their speaker.

Sir Edward is the longest continuously serving MP, having had a seat in the Commons since 1983 – the year when Margaret Thatcher won a 144-seat majority and when Jeremy Corbyn, Tony Blair and Gordon Brown first became MPs.

He must preside over the selection.

Sir Lindsay Hoyle is expected to put himself forward as Speaker, having served in the role since 2019 and contested the Chorley, Lancashire, without a party affiliation.

It is up to MPs to decide whether he will stay on in the role.

If Sir Lindsay is allowed to remain in post, MPs will drag him to the Speaker’s Chair to serve in the once-perilous role, seven speakers were executed by beheading between 1394 and 1535, according to Parliament records.

Sir Lindsay is expected to thank his colleagues, and senior politicians may also speak to congratulate him, including Sir Keir.

Swearing in begins the same afternoon, led by the Speaker, Father of the House Sir Edward, then members of the Sir Keir’s Cabinet and Leader of the Opposition Rishi Sunak’s shadow cabinet.

Lawmaking and debates in the House of Commons remain on hold until after the formal State Opening of Parliament, a ceremony at 11.25am next Wednesday, where the King will read a speech from the Sovereign’s Throne in the House of Lords, setting out the Government’s agenda.

While MPs wait for the Labour Government’s plans in full, opposition parties have already begun setting out their priorities.

Liberal Democrat leader Sir Ed Davey has accused the Conservatives of leaving the NHS “at crisis point”.

His party has called for an emergency budget to pump more money into health and social care.

“Patients cannot wait any longer after years of Conservative chaos which has left NHS and social care services at crisis point,” Sir Ed said.

“As I travelled the country in recent weeks, I heard devastating stories of pensioners waiting hours for ambulances, young parents waiting weeks for a GP appointment, too many left with anxious waits for cancer care.

“We need an emergency Health and Social Care budget to get the NHS back on its feet after the Conservative party brought it to its knees. Patients and their loved ones need to get the care and the fair deal that they deserve.

“New Liberal Democrat local champions will fight in Westminster to restore local health and care services after years of neglect.”

The Green Party has made a series of demands – among them to “settle a pay deal with junior doctors”, “prosecute major water companies” which discharge sewage into rivers and seas, develop a “local rail link plan”, “recognise the state of Palestine” and “introduce a Natural History GCSE”.

Adrian Ramsay, the party’s co-leader, said: “These are not lofty ideals but practical actions that can be implemented quickly.

“They will have a real, positive impact on people’s lives and the environment.

“I am delighted that as we meet to enter parliament Labour have already committed to reversing the de facto ban on onshore wind. Now they must go further and faster still and make solar power mandatory on all suitable new build homes.

“They can, and they must do this in their first 100 days.”