A former chief adviser to the late Queen has revealed the “seat of the pants” crisis talks that took place after Boris Johnson was admitted to intensive care with Covid, including discussion of “scenario C” over what would happen if he died.

Lord Young of Old Windsor also lifted the lid on how he and the then prime minister’s top aide Martin Reynolds had intervened at the last minute to stop a face-to-face meeting between the vulnerable monarch and the unknowingly infected Tory leader, averting potential disaster.

The independent crossbencher broke his silence on the behind-the-scenes drama at the centre of power in the early days of the coronavirus emergency in 2020, as he stressed the importance of an impartial Civil Service “when things go wrong” and the constitutional “rulebook runs out”.

Prime Minister Boris Johnson makes a statement outside 10 Downing Street in April 2020 after spending two weeks recovering from Covid-19
Prime Minister Boris Johnson makes a statement outside 10 Downing Street in April 2020 after spending two weeks recovering from Covid-19 (Stefan Rousseau/PA)

Lord Young served the late Queen for nearly two decades, latterly as principal private secretary until her death in 2022, and remained in post to oversee the transition to the reign of King Charles III.

Speaking in a Lords debate in Parliament on concerns over the politicisation of Whitehall, Lord Young said: “My contention is that a neutral Civil Service is vital in supporting the channels of communication, the constitutional channels between state and government especially in a crisis, especially in the context of the unwritten constitution we have, which is 99% reliant on precedent and 1% seat of the pants when things go wrong.”

He told peers: “Before I came to the House I was for many years private secretary to the late Queen and I’d like to offer an illustration of what happens when that 1% occurs in a crisis.”

He recounted events from early April 2020 that saw Mr Johnson admitted to hospital with Covid-19, shortly after the imposition of the first lockdown.

Lord Young said: “In recalling this illustration I am very conscious of the omerta principle that I am signed up to and as you would expect I sought permission from those who I will name.”

He went on: “It was the early evening of Monday April 6, it was pouring with rain, I was walking home from Buckingham Palace, the Queen had just moved to Windsor Castle.

“I stopped at a bus shelter to take a call from the excellent Martin Reynolds, the principal private secretary to Boris Johnson.

“We knew that the prime minister had gone into hospital the night before.

“But his protection officers had overheard some consultants discussing how they were going to tell Carrie (his now wife) that he might have to go into ICU and on to a ventilator.

“Clearly, I had to update the Queen on this.”

Lord Young added: “We had our suspicions, because, just the previous Wednesday, the final face-to-face audience at Buckingham Palace had been scheduled.

“The prime minister considered it his duty to be there to do it face to face and the late Queen considered it her duty too – in a sort of Blitz spirit, ‘Well, I’ve got to die sometime’ attitude – but it really was not the moment for taking unnecessary risks.

“In the end, both participants were so keen to go ahead with it that Martin and I arranged for him to tell the prime minister that the Palace wanted to cancel and for me to tell the Queen that Number 10 had got cold feet, which was very lucky, because, by the end of the telephone call… the prime minister had started coughing.”

The next day he received a call from the then cabinet secretary Mark Sedwill, now Lord Sedwill, that Mr Johnson had tested positive for Covid.

Lord Young said: “So there was a scenario that we had avoided, luckily, of an unknowingly positive head of government being in proximity to a strong but vulnerable head of state, and history might have taken another constitutionally taxing path.”

With Mr Johnson subsequently admitted to hospital, Lord Young recalled the ongoing discussions as he sat on his mobile phone in a “rainy bus shelter near Battersea”.

He said: “There was no deputy prime minister, there was no precedent to draw from.”

Referring to the only prime minister to be assassinated whilst holding office, Lord Young said: “Yes, Spencer Perceval had been shot and died, there was some precedent there but not for a prime minister who was alive but unable to communicate for an unforeseen period of time.

“It was the impartial nature of the discussion of what was described as scenario C – the euphemistic, anodyne-sounding scenario which was really about what would happen if the prime minister died – that was so important.

“The impartial nature of the advice that I was receiving from the cabinet secretary and the principal private secretary, enabling me to report to Her Majesty in supporting her as head of state, was crucial.

“It put state before government and certainly before patron.

“It is crucial when the rulebook runs out to be able to rely on people who have clear judgment to be able to navigate the space between the lines.”