The scale of the revolt against Chief of Staff Sue Gray inside Downing Street is unprecedented – and has set ‘the clock ticking’ down to her departure.Of the 12 senior civil servants who comprise the Prime Minister’s Private Office, three have already left, five have asked to be moved and the remaining four have downed tools and are threatening to quit.Sir Keir Starmer’s most senior aide, his Principal Private Secretary Elizabeth Perelman has moved, as planned, to the Cabinet Office.But Ms Gray amid a barrage of negative publicity about ‘cronyism’ in the administration has so far failed to install her preferred replacement, former colleague Daniel Gieve.The main issue, as The Mail on Sunday revealed in August, is that Ms Gray is excluding the officials from prime ministerial meetings concerning their departmental areas, instead, giving them a ‘readout’ afterwards to pass on.The effect has been to demoralise and infuriate staff. Chief of Staff Sue Gray did the talking at this tense meeting with Michael Bourke in this exclusive picture from the NEWSWALLALast week’s row over Ms Gray’s £170,000 salary being £3,000 higher than the Prime Minister’s has even led to talks of Downing Street special advisers (spads) going on strike: she has been advised that it would be ‘unwise’ to continue to attend the cross-Governmental spad meetings: Morgan McSweeney, Starmer’s head of political strategy, is attending in her place. It is a victory for Mr McSweeney, who masterminded Starmer’s leadership campaign and ran the triumphant general election operation, but who has been engaged in a battle with Ms Gray for access to the Prime Minister.Dozens of the spads, many of whose salaries have been cut to below the levels they were paid when working for the Labour Party in Opposition, have joined a branch of the FDA, the Civil Service union to fight back against Gray’s influence.A source said: ‘This cannot last. Sue has made enemies of all stripes. Downing Street has suffered an exodus of good people, and the operation has been paralysed. It surely cannot be long before 66-year-old Gray is shunted off to the Lords and given a ministerial job to keep her quiet.’The dysfunction was highlighted by the exclusive picture published on the front of yesterday’s NEWSWALLA, which showed Ms Gray locked in tense talks with Michael Bourke, the principal private secretary to Cabinet Secretary Sir Simon Case.An onlooker said: ‘I was watching them for about 10-12 minutes. It was unbelievable – it certainly wasn’t a nice conversation. He looked upset and she wasn’t smiling at any point. ‘After Gray left, the poor chap was vaping with his head in his hands. I couldn’t hear what they were saying as they were a long way away, but I’ve never seen anything like it before in Downing Street.’Sir Simon, the head of the Civil Service, has also been locked in a battle with Ms Gray for access to the PM. Sir Simon has been tasked with investigating the leaks about Ms Gray, leading one of the few allies of Ms Gray – without any proof – to say he ‘should start by investigating himself’. Case is widely expected to leave Downing Street by the end of the year, but is reluctant to hurry out the door.Helping to salvage the malfunctioning No 10 operation are Chancellor Rachel Reeves and Pat McFadden, the Chancellor of the Duchy of Lancaster, who effectively operate as joint deputy Prime Ministers. Sir Keir’s actual Deputy, Angela Rayner, has been elbowed out of the so-called Quad which was said to be taking the key decisions in Government.A No 10 source said: ‘It is no longer the Quad – it is the Holy Trinity. Angela doesn’t have a proper Office of the Deputy Prime Minister. She doesn’t have the side-annexe typically occupied by officals – her aides are all back in the Housing Department. The three key people are Keir, Pat and Rachel. They run the Government. If Pat and Rachel agree on something, Keir will always do it.’While Ms Rayner and Chief Whip Sir Alan Campbell join the daily 8.30am meeting with officials, Mr McFadden chairs a separate meeting straight afterwards which is about ‘implementation’.The source said: ‘The 8.30 is where the direction is set. But it’s Pat who is charged with delivery.’The controversy surrounding Ms Gray has denuded her power and made her wary of challenging the Trinity. This was highlighted recently when her plan to secure a £310 million taxpayer-funded redevelopment of Casement Park, a derelict stadium in Belfast where two British soldiers were murdered by nationalists in 1988, was vetoed by the Trinity.A source said: ‘Sue is causing trouble all over the place. But she has realised she can’t cut across anything Keir, Pat and Rachel decide. It would be complete chaos without their hands on the tiller. The clock is ticking for Sue.’A No10 spokesman said: ‘These claims are categorically untrue.‘It is not true that Sue Gray is doing the PPS job – that is being done by the deputy PPS. Recruitment is ongoing. We don’t recognise your characterisation of the Private Office.’A No 10 source added: ‘As you’d expect Sue meets spads all the time – every day. That meeting is chaired by Morgan, as it has been since we came into office. Any suggestion of changes to that is untrue.’