Mary Stuart: Rise and rise of the invisible man... how a York schoolboy controls corridors of power

And yet Sir Jeremy has achieved the remarkable feat of being made Britain’s new “Sir Humphrey” aged just 50. He has the toughest of acts to follow, succeeding “GOD”: well, Gus O’Donnell, who announced his retirement from Whitehall last autumn.

Michael Allen, now a retired deputy head of Bootham School, recalls that Heywood’s meteoric rise began when he won a scholarship to Oxford, despite his fears that his economics wasn’t then up to scratch.

How ironic then that he would go on to do his Masters at the LSE in economics before ending up as Private Secretary to Norman Lamont, the Chancellor of the Exchequer during “Black Wednesday” in September 1992, when the pound was devalued. Coincidentally, it was at this point that he met a young David Cameron, then special adviser to Lamont.

By this stage, Heywood had become known for his deft diplomatic skills. John Major recalls in his memoirs that during the crucial Maastricht negotiations in December 1991 how Heywood helped to recover a lost briefing document, averting the embarrassment of it falling into the wrong hands.

Heywood’s early Conservative connections made him ripe for promotion under a true blue Government.

So it might come as a surprise to learn that he was selected by Tony Blair to serve as his Principal Private Secretary in 1999.

Blair came to admire Heywood’s radical zeal, especially in relation to reforming the public services. Heywood also made himself unpopular with his fellow civil servants, pushing through tough efficiency drives, involving massive job cuts.

Such a reputation might have brought him into conflict with Gordon Brown, but instead, Heywood, it is said, acted as a peacemaker in the torrid “TB-GB” relationship, fitting for a man who keeps a bust of Gandhi on his mantelpiece.

After a short spell at the investment bank, Morgan Stanley, Heywood returned to the heart of Government in 2007 as head of domestic policy and strategy at the Cabinet Office, charged with the task of lending some stability to the Prime Minister’s otherwise chaotic government.

In January 2008, he became the first Permanent Secretary at Downing Street, in effect, Brown’s right-hand-man, a role he retained after David Cameron became Prime Minister last year.

But despite his illustrious career thus far, you could be forgiven for reacting to news of Bootham School’s latest successful-former-pupil-made-good with a question: “Who’s Jeremy Heywood?”

It’s difficult to believe that even before he took up his new role, Heywood was listed as the third most influential man in Britain by GQ magazine, just ahead of Prince William no less.

Rarely in politics has such a powerful figure been quite so invisible from the public eye.

Dig a little deeper, however, and it is possible to see a moment of controversy that may come to dog Heywood’s otherwise unblemished career.

In 2003, Heywood failed to take minutes during a series of meetings with senior officials and cabinet ministers prior to the release of Dr David Kelly’s name to the media. Lord Maurice Hankey, Lloyd George’s Cabinet Secretary, who wrote down the first ever Cabinet minute in 1916, would have turned in his grave.

There have been only 10 Cabinet Secretaries since the post was invented under Lloyd George. Many holders of the office, such as Sir Burke Trend (1963-1973) served for years with scrupulous impartiality.

More recent holders of the post, particularly Sir Richard Wilson (1998-2002), were drawn into the “sofa government” of Tony Blair, and Heywood stands accused by his critics of fitting into that mould. Ideally, profilers of Heywood would have wished that he had risen from head boy (or “reeve” as it is known at Bootham, where his father Peter also taught as Head of English) to Head of the Home Civil Service.

But that neat symmetry has been upset by the fact that this role will be the responsibility of another Whitehall mandarin.

At first sight, it looks as if Heywood has had his wings clipped, but on closer inspection, Cameron wants his new Cabinet supremo to devote all his time to being in personal charge of delivering on the Government’s reform agenda: in short, acting as an enforcer.

In that respect, perhaps it isn’t a surprise after all that the newly knighted Sir Jeremy has survived under both Blair and Cameron.

In terms of public service reform, Cameron still sees himself as the “heir to Blair”, and it seems as though he has brought Heywood into the heart of government in order to carry on that agenda further and faster, in an effort to shrink the size of government in an era of economic austerity.

That task is bound to prove controversial, so one thing is certain: the relative anonymity that Sir Jeremy has enjoyed up until now won’t last for much longer.

• Mark Stuart is a political writer from York who has written biographies of John Smith and Douglas Hurd.