THERESA May will today attempt to claw back some authority at Westminster with a sweeping reshuffle that could see half a dozen senior ministers moved or given the chop.

Confirming the shake-up of her cabinet, the Prime Minister also said she intended to stay in Downing Street “as long as people want me”.

Education Secretary Justine Greening is most heavily tipped for an exit, alongside Business Secretary Greg Clark, leader of the House of Commons Andrea Leadsom, and Tory party chairman Sir Patrick McLoughlin, who was much criticised after June’s election losses.

The big four of the cabinet - Chancellor Philip Hammond, Home Secretary Amber Rudd, Foreign Secretary Boris Johnson and Brexit Secretary David Davis - are all understood to be staying in post, despite recent predictions of a sideways move for Mr Johnson.

The reshuffle is a delayed response to the effective sacking of Mrs May’s most trusted cabinet colleague Damian Green just before Christmas.

The First Secretary and effective deputy PM admitting lying about pornography being found on his office computer during an office raid in 2008, while he was in opposition.

He had described a newspaper report on the discovery as “inaccurate and misleading”.

In November, Mrs May was forced to replace two other cabinet secretaries who resigned in disgrace - Michael Fallon and Priti Patel - but carried out very limited reshuffles.

The new changes, which are expected to start today and continue tomorrow, are expected to be far more wide-ranging.

It is thought Mrs May will bring forward some junior ministers, with Immigration Minister Brandon Lewis and Justice Minister Dominic Raab tipped for the top.

Promotions are also predicted for several younger female MPs in an effort to banish the “pale, male and stale” image of the Tories.

A key appointment for Scotland will be the next

secretary with responsibility for the Cabinet Office, which takes an overview of devolution.

Mr Green held the role until his sacking, and was integral in the talks between the UK and Scottish Governments over Brexit and the repatriation of powers after March 2019.

His successor will inherit the role with the Scottish Government arguing the current Brexit legislation must be significantly rewritten before Holyrood gives its legislative consent.

If Holyrood were ultimately to withhold its consent, it could trigger a constitutional crisis.

Scottish Secretary David Mundell is not expected to be moved out of his post.

Amid rumours Mrs May would like to make Health Secretary Jeremy Hunt her deputy, the SNP said it would show “contempt” for the NHS given the winter crisis choking hospitals.

In an interview on the BBC’s Andrew Marr show on Sunday, Mrs May said: “Damian Green’s departure before Christmas means that some changes do have to be made, and I will be making some changes.”

Mrs May was also asked whether she intended to fight the next general election - due in 2022 - as Conservative party leader.

She replied: “I’ve been asked that before and I’ve said, I’m not a quitter. I’m in this for the long term. I’ve said that I want to fight that [the next election] before.”

But she added: “Obviously, I serve as long as people want me to serve.”

In the interview, Mrs May also defended her Government's handling of the NHS winter crisis south of the border, saying "nothing's perfect" in the health service, and confirmed a review decision-making at the Parole Board after the release of “black cab” rapist John Worboys.

Downing Street sources sought to play down the reshuffle reports as "speculation" and "guesswork".

SNP MP Dr Philippa Whitford said it would be disgrace if Mr Hunt was rewarded for failure.

She said: “After the damage that Jeremy Hunt has done to the NHS in England it would be foolish for the Prime Minister to promote him to become her deputy. It would show utter contempt for the NHS.

“There’s only one place he should be reshuffled - and that’s out of the health brief and straight to the back benches, where he can do no further harm to public services.”