Sir Keir Starmer is being warned that his party’s Brighton conference is “falling apart” following the dramatic resignation of a shadow minister.

The Labour leader has been rocked by Andy McDonald’s decision to quit as shadow secretary of state for employment rights and protections midway through the party’s gathering on the South Coast.

Mr McDonald’s resignation, which the left-winger announced with a blistering attack on Sir Keir’s leadership and policies – including a claim he was blocked by the leader’s office from voicing his support for a £15 per hour minimum wage – has prompted a fresh bout of Labour infighting.

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And those who had supported Sir Keir’s predecessor, Jeremy Corbyn, might look to turn up the pressure on the Labour leader when many of them speak during a rally at the left’s alternative conference, The World Transformed, in Brighton on Tuesday.

“To be honest, the conference is falling apart because of the behaviour of the leader – it’s appalling,” said former shadow chancellor John McDonnell, who is among those listed to speak at the Socialist Campaign Group rally.

Mr McDonald’s resignation came hours after former Labour MP, Dame Louise Ellman, announced she was rejoining the party nearly two years after she had quit Labour over antisemitism and Mr Corbyn’s leadership.

But, despite the drama, there were claims that Sir Keir’s office had “no sense of loss” over Mr McDonald’s departure and “no tears” were being shed.

And, on the eve of his first in-person conference speech as party leader, Sir Keir will on Tuesday look to wrestle the focus of the conference back onto how he is trying to move Labour on from Mr Corbyn’s era.

This will include some of Sir Keir’s key shadow cabinet allies attempting to take the fight to the Conservatives on the issues of law and order, health and education.

Shadow home secretary Nick Thomas-Symonds will use his conference speech to accuse the Tories of being “soft on crime and soft on causes on crime”.

He will also announce Labour’s new plans for increased visible policing with “eyes, ears and boots on the ground”.

“In Tory Britain, people say you never see police on the beat any more,” Mr Thomas-Symonds is expected to say.

“That school children feel afraid at the bus stop, that people feel unsafe going out after dark. This is the price of years of Tory cuts to neighbourhood policing.

“With me as home secretary – if there is trouble on your street Labour will make sure that someone is there. You will see officers on the beat.

“In every community where people are frightened and afraid there will be a new police hub, and new neighbourhood prevention teams which bring together police, community support officers, youth workers and local authority staff to tackle anti-social behaviour at source.”

Meanwhile, Labour’s shadow health secretary Jonathan Ashworth will accuse the Conservatives of having failed to put in place a plan to tackle NHS waiting lists or to improve social care.

“The NHS is in crisis not simply because of COVID,” he is expected to say.

“The NHS is in crisis because of the Conservatives. A crisis that sees NHS services collapsing, the army called in to the aid of ambulance trusts.

“Hospitals ration chemotherapy. And more and more people taking out loans, crowd-sourcing for donations in pain and desperation.”

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Labour’s shadow education secretary Kate Green will also challenge the government to deliver a coronavirus crisis “recovery guarantee” for school children.

“Our children’s futures, life chances and aspirations must not be limited by the Conservatives treating them as an afterthought,” she is expected to say.

“They must not be limited by a recovery plan that the government’s own catch-up expert described as ‘feeble’.

“And they must not be limited by a weak prime minister who took months to sack a failing secretary of state.

“That is why today, conference, I am challenging the new education secretary [Nadhim Zahawi] to deliver a recovery guarantee.

“To ensure that every single child who has been let down, ignored and undervalued by this government not only recovers from the pandemic, but thrives on new opportunities to learn, play and develop – just as Labour’s plan would enable them to do.”