Lord Geidt had been the late Queen’s private secretary for 10 years.
His tenure came to an abrupt end amid differences over how to manage the transition of power between the late monarch and her eldest son.
When told he had been let go, the new Prince of Wales is said to have gone to see Earl Peel, the Lord Chamberlain, to give him a piece of his mind.
“He was really angry about it, not necessarily because it was the wrong decision,” said a source.
“He just thought it was handled very unkindly for a man who was a pillar of the institution of the monarchy, but had also played an incredibly important role when the coalition government had been formed.”
Lord Geidt ‘bruised’ after power struggle
Lord Geidt had fallen foul of the Duke of York when, during the Diamond Jubilee celebrations in 2012, he supported Charles’s bid to present a slimmed down version of the monarchy on the Buckingham Palace balcony.
Rather than the traditional scenes of the wider Royal family cramming onto the balcony for the flypast, just the late Queen and the then Prince of Wales and Duchess of Cornwall, Duke and Duchess of Cambridge and Prince Harry stepped out before the crowd.
It was a deliberate act to convey a message about who really mattered in the Royal family – but for the Duke of York, Low claimed it was “like a dagger to his heart and he hasn’t got over it”.
In 2014, Lord Geidt’s attempts to create a streamlined royal communications operation, bringing all households under one umbrella, did not go down with Charles III, who is alleged to have felt that his power base was being undermined.
In May 2017, when the Duke of Edinburgh retired from public life, he told staff that all members of the Royal family and their households should unite and act collectively in support of Queen Elizabeth.
That message also proved problematic, the book claimed, with fears abounding about the merging of households. Younger royals were also left with the impression they were being told to do less of their own campaigning work.
A few weeks later, the late Queen’s eldest two boys are said to have joined forces to tell the monarch: “Geidt has got to go.”
Lord Geidt, who went on to work as an ethics adviser to Boris Johnson before resigning earlier this year, was said to have been “very bruised” by the brutal manner in which his downfall was orchestrated.