Foreign Secretary Jeremy Hunt – who previously served as health secretary – praised the “tireless” work of Sir Jeremy in getting the additional funding for the health service.

The revelation of the critical role played by former cabinet secretary Sir Jeremy, who served four prime ministers, underlines the influence he had behind the scenes at the heart of government.

The respected Whitehall mandarin, who been cabinet secretary since 2012 and head of the home civil service since 2014, retired less than two weeks ago following medical advice.

Prime Minister Theresa May said Sir Jeremy, who was 56, would be “sorely missed”.

“He worked tirelessly to serve our country in the finest traditions of the civil service and he is a huge loss to British public life,” Mrs May said.

“I will always be grateful for the support which he gave me personally and will remember his achievements across his career as we regret that he did not have the chance to offer his talents for longer in retirement.”

In recognition of his distinguished service, the PM had nominated Sir Jeremy for a life peerage as Lord Heywood of Whitehall.

Image: Sir Jeremy, pictured third from left, had served as cabinet secretary since 2012 Image: Sir Jeremy has been described as 'a wonderful public servant'

Mr Hunt said in a Twitter post: “Few doctors and nurses will know this but there would absolutely not have been an extra £20bn for the NHS without Jeremy Heywood‘s tireless working behind the scenes.

“One of many examples of his extraordinary service to us all. Smart, loyal and decent, we will sorely miss him.”

Sir Jeremy had previously served as principal private secretary to prime ministers Tony Blair and Gordon Brown, and worked as chief of staff to Mr Brown and Downing Street permanent secretary to David Cameron.

The father-of-three revealed earlier this year that he had been diagnosed with cancer in June 2017, but had stayed in post amid the ensuing political turmoil following the shock general election result.

Image: Tony Blair says Sir Jeremy served with 'integrity, distinction and infinite commitment'

In a statement, Sir Jeremy‘s wife Suzanne paid tribute to a “wonderful father” who “crammed a huge amount into his 56 years”.

She said: “He saw it as a huge privilege to work so closely with four prime ministers and two chancellors and was unwavering in his efforts to help each of them reach their goals.

“He was always conscious of the need for civil servants to see the world through ministers‘ eyes while at the same time respecting the boundaries between politicians and civil servants.

“Away from his work, he inspired admiration, respect and affection in his many and diverse group of friends and returned it to them.

“Jeremy could light up any room or conversation and loved hosting a good party.”

Mr Blair said: “He worked with more prime ministers and at a more senior level than any civil servant in recent memory and served us all with integrity, distinction and infinite commitment.

“The British civil service and all of us who worked with him will miss him deeply.”

Mr Brown added: “The country has lost a leader of exceptional ability, unquestioned integrity and – as we saw in the way he fought his illness – remarkable courage.”

Sir Jeremy‘s predecessor Lord O‘Donnell wrote in a tweet: “He was a great, dedicated civil servant who worked tirelessly for his country, his political masters and his colleagues.

Reacting to the breaking news on Sophy Ridge on Sunday, Labour‘s former cabinet minister Yvette Cooper said: “It‘s deeply sad. Jeremy was a wonderful public servant and he did a huge amount to hold governments together at very difficult times. I obviously knew him very well personally.

“People will not be aware of quite how many remarkable things he did to solve crises, to deal with some of the most difficult problems and as a very honourable public servant to hold people together and to make sure that the government frankly didn‘t do stupid things on many occasions and to make sure there were solutions.

“His contribution to public life for all governments, whatever your politics, his contribution to public life was immense and I think we all owe him a debt of gratitude.”

Liberal Democrat leader Sir Vince Cable also told Sophy Ridge on Sunday: “He was a superb public servant. He was brilliant in getting his head around complicated problems.”

Sir Mark Sedwill, who succeeded Sir Jeremy as cabinet secretary and head of the civil service, said: “Jeremy was the exemplary public servant. We will miss him more than we can say, and will be the poorer without his advice, leadership and extraordinary insight.”