The Labour leader has been told that now is the time to be "bold" in shaking up his top team ahead of next year's general election - but it is unclear at this stage whether Sir Keir intends to make only limited changes or will carry out a more substantial re-organisation.

There are two schools of thought regarding what form the reshuffle could take.

The first is that all posts outside of Sir Keir's five key missions could be up for grabs, or that the reshuffle could be minor and possibly mirror changes in government departments - for example, to cover posts such as secretary of state for science, innovation and technology which is occupied by Michelle Donelan but does not have a Labour counterpart.

However, senior Labour sources who spoke to Sky News said Sir Keir should use the reshuffle as an opportunity to promote new names into the shadow cabinet - which they said would de facto would make it significant.

There has been frustration that previous opportunities to carry out a reshuffle, such as immediately after the May local elections and after three by-elections in July, were not taken - with the party's defeat in Uxbridge holding part of the blame.

One Labour adviser told Sky News: "It's time to shake things up and get the talent in where it belongs. We need to show the country how we will transform Britain."

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Another source added: "Keir talks a lot about being ruthless - he should stick to that.

"This isn't just the next shadow cabinet, it's potentially the next government. People shouldn't just stay because he's afraid to rock the boat. He's in his strongest possible position - it's a waste if he doesn't act now."

Among the names of those have been tipped for a possible promotion include Darren Jones, who currently chairs parliament's business and trade committee, and shadow policing minister Sarah Jones.

Mr Jones has been widely tipped for months to take on the role of shadow science, innovation and technology secretary - a position that is currently vacant and is also said to be coveted by Lucy Powell, who currently holds the culture brief.

Sources said Ms Jones, the MP for Croydon Central, could take on the brief of Northern Ireland secretary due to her background in policing.

That role could be vacated by the incumbent, Peter Kyle, who sources said would be well-placed to take on the environment, food and rural affairs brief due to the "political capital" that can be made due to the current crisis of sewage in rivers and seas.

Mr Kyle, the MP for Hove, is viewed by one member of the Labour frontbench as ideal for the role.

"It's not seen as a top job, but he could really land blows on Tories," they said. "Especially in coastal and rural areas where we'd like to win seats."

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Alison McGovern, the current shadow minister for work and pensions, was described as the "obvious" choice to take on the culture brief given her advocacy for women's football in the year of the Women's World Cup.

However, Thangam Debbonaire, the current shadow leader of the House, has also been mentioned for the role given her background as professional cellist and as MP for Bristol West, a constituency known for its creatives.

Other names that could be vulnerable to being moved are Louise Haigh in transport, Jo Stevens in the shadow Wales office and shadow mental health minister Rosena Allin-Khan - who could be replaced by Liz Kendall.

Key players staying put

While the reshuffle could see movement around the margins, shadow cabinet ministers orientated around Sir Keir's five missions are expected to stay put.

It means that shadow chancellor Rachel Reeves, shadow home secretary Yvette Cooper, shadow health secretary Wes Streeting, shadow education secretary Bridget Phillipson and shadow climate change secretary Ed Miliband are likely to stay in post until the next election.

But there are questions about other heavy hitters, including shadow levelling up secretary Lisa Nandy - who has been rumoured for a demotion or possible move out of the entire shadow cabinet - and Angela Rayner, with whom relations have been strained.

While Ms Rayner cannot be moved from her role as deputy leader given it is an elected position, she occupies an array of other roles including the shadow chancellor of the duchy of Lancaster and shadow secretary of state for the future of work which some of Sir Keir's aides are reportedly keen to move her from.

There are fears that the future of work brief occupied by Ms Rayner could be watered down or scrapped entirely amid fears that it requires too much input from trade unions.

Her allies have remained tight lipped about any move - but past briefings have suggested that Ms Rayner could be moved to Ms Nandy's role in a bid to move her away from the levers of the future Cabinet office.

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However, some question the logic of moving Ms Rayner to a brief where she could become the "voice of the North" in Westminster and challenge the Treasury on spending decisions.

It could, they suggest, also allow her to build up a rival power base along with other metro mayors, as well as forge close ties with local constituency parties needed for a potential leadership bid.

Sources also pointed out that Sir Keir would not want to see a repeat of the chaotic 2021 reshuffle, in which he sacked Ms Rayner as party chair and national campaign co-ordinator only to appoint her to the roles she occupies currently.

At this stage the one thing that stands out is the desire for Sir Keir to make his biggest power play yet - but whether he will remains uncertain.