His enemies call him the ‘PM’s puppet-master’. Blair, Brown and Cameron all found him invaluable. He’s been at the heart of the most controversial political episodes of recent times. Just who is Jeremy Heywood?

It is easy to miss the Cabinet Office on Whitehall in central London. To the uninitiated, it is just another bone-coloured, net-curtained facade in the unreadable heartland of British government. Seemingly the only noteworthy thing about the building is that its Victorian bulk stands directly between 10 Downing Street and the outside world. Most visitors to the prime minister have to get past the Cabinet Office first.

Since 2012, the head of this department, the cabinet secretary, has been Sir Jeremy Heywood. In the historian Peter Hennessy’s book Whitehall, one of few successful attempts to explain Britain’s labyrinthine and unusually dominant central government, the Cabinet Office, set up exactly a hundred years ago, is described as the “coordinating brain for the whole system”.

Since well before 2012, Heywood has been the most powerful person in Britain that most people have never heard of. “He is the person who is always in the room with the prime minister, the person who is always there on the conference call,” says a former head of the Downing Street Policy Unit (even Heywood’s former colleagues usually prefer to talk about him off the record). He was economic and domestic policy secretary to prime minister Tony Blair from 1997 to 1998, and his principal private secretary from 1999 to 2003; head of domestic policy for prime minister Gordon Brown from 2007 to 2008; and Downing Street permanent secretary, first for Brown and then for David Cameron, from 2008 to 2011.

Through two temperamentally opposed Labour administrations, the turbulent Conservative-Liberal Democrat coalition, and into the current, dominant-but-brittle Tory government, Heywood has been a uniquely influential constant in Downing Street: a fixer and an enforcer, a confidant and a coordinator, a peacemaker and a crisis manager, an assessor of policies, an interpreter of protocol, a relentless accumulator of responsibilities and contacts and institutional knowledge, a conductor of internal inquiries, a keeper of secrets. A former Downing Street chief of staff says: “Jeremy’s like a drug. People get addicted to him quite quickly. Prime ministers are not sure about him at first. Then they say, ‘Umm, that’s rather good. I need that.’”

Jeremy’s like a drug. People get addicted to him quite quickly

His one absence from Downing Street was a senior job at the American bank Morgan Stanley between 2003 and 2007. And even that was interrupted by cravings for Heywood from No 10. As soon as Brown became prime minister in 2007, one of his closest allies says: “One of our priorities was to get Jeremy back from the City.”

Heywood has been so central to British government for so long that few of its most contentious modern episodes have not involved him: the Iraq war and its aftermath; the hasty formation of the coalition; the Conservatives’ encouragement of Rupert Murdoch’s abortive bid for BSkyB; the News of the World phone-hacking scandal and Cameron’s employment of its former editor Andy Coulson; the alleged gagging of ministers over airport expansion and the EU referendum; the row over British plans to restrict benefits for EU migrants; the Plebgate affair that ruined the government chief whip Andrew Mitchell; the government’s refusal to release official papers on the treatment of trade unionists and other Tory foes during the 1970s and 1980s; the attempted silencing of the National Security Agency whistleblower Edward Snowden.

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Confirmed Heywood interventions are rare. In June 2013, he visited this newspaper and warned its then editor, Alan Rusbridger, that the Guardian’s involvement with Snowden could make it a target for “our guys” in British intelligence and “Chinese agents on your staff”. In September 2014, just before the Scottish independence referendum, the Queen made a carefully loaded public statement which bent the rules of royal impartiality to the advantage of the no campaign. “I hope people will think very carefully about the future”, she told a crowd near her Scottish residence at Balmoral. Heywood had co-written it with her private secretary, Sir Christopher Geidt.

Much more often, Heywood’s exact contribution to government policies and decisions is the subject of rumour and counter-rumour, of briefings by underlings and allies and enemies. Only his ubiquity and importance are universally agreed on. “He has the ability to be 24/7 in Downing Street but also well-connected to the outside world. He has sources in other government departments,” says a former head of the Downing Street Policy Unit. Another former colleague of Heywood’s from Downing Street says: “Jeremy would quite often think he could do things better than someone else, that a project would be improved by a bit of Jeremy input.”

There is no official manual that sets out what the cabinet secretary is supposed to do. Last year Heywood sketched some of his activities for one of Cameron’s biographers, Anthony Seldon. “Every morning, we kick off with a prime minister’s meeting. Sometimes we have an afternoon meeting as well … I help the prime minister to think through what should be on the cabinet agenda. I sit next to the prime minister in cabinet, and take a record of what’s been discussed … [then] making sure that is followed through.”

Like almost everything Heywood says in public, the tone was informal, unstuffy, seemingly straightforward. For anyone who learned about cabinet secretaries from Sir Humphrey Appleby, the grand, gleefully manipulative holder of the post in the 1980s television satire Yes, Prime Minister, Heywood can initially appear a disappointment. He is a northerner, as his vowels sometimes show despite over a quarter of a century in Whitehall. He speaks quietly and without drama. In his palatial office, all wood panelling and chandeliers, his desk is small and nondescript and unshowily tucked into a corner. He sometimes receives visitors with his jacket off, and, at 54, still wears his hair in a boyish quiff. In his rimless glasses, with his tirelessly precise sentences, he is more like a senior accountant or a top management consultant than the pinstriped mandarins of civil service legend.

But power in Whitehall has always come in many guises. The more you ponder Heywood’s roles as he described them to Seldon – “I help the prime minister to think”; “making sure” cabinet decisions are “followed through” – the larger they seem. “He understands how to make this massive machine move,” says Rohan Silva, who was, between 2010 and 2013, a key member of the Downing Street Policy Unit. “He reads everything. He works harder than anyone I’ve ever worked with. If you CC him on an email, it clears a path through the bureaucracy. But he wears it all very lightly. The PM and the chancellor just think he’s great.”

Last year, Heywood was also made head of the civil service. Alongside his backstage Downing Street role, he became the public face and boss of an organisation of 390,000 employees, which, in the austerity era, is going through possibly the most brutal job cull in its history. “For many people this [job] would be one of the biggest things they did,” Heywood told a recent gathering of senior civil servants and Whitehall-watchers at the Institute for Government. “It is just number five on my list.”

Heywood has made enemies. To the conservative magazine the Spectator, he is “the PM’s puppet-master”, curbing Cameron’s more innovative impulses to protect Whitehall’s interests; or “‘Wormtongue’ after Tolkien’s poisonous power behind the throne in the Lord of the Rings”. To the Daily Mail, he is the “eminence grease”, “Whitehall’s most cynical mandarin”, and “Sir Cover-up”, allegedly responsible for undermining the Freedom of Information Act and the Chilcot inquiry into the UK’s role in the Iraq war.

In 2011, even before Heywood’s most recent promotions, the perceptive rightwing commentator Peter Oborne wrote in the Daily Telegraph that Heywood was “a perfect manifestation of everything that has gone so very wrong with the British civil service over the past 15 years – too cosy a relationship between public and private, too much dominance at the centre, contempt for tradition and the collapse of due process.” In 2013, the Times reported that Heywood was becoming “an increasingly controversial figure in Whitehall”: “not explicitly disloyal” to ministers with whom he disagreed, but “unhelpful to the government”. Heywood had allegedly told a recent meeting of bankers that “his job was being made harder by the differing priorities of senior government figures”, as if one of the government’s objectives ought to be making his job easier.

Heywood also has critics on the left. To the Labour MP Paul Flynn, he is “a politician who thinks he’s a civil servant, and a civil servant who thinks he’s a politician”; “slippery” and lacking the civil service’s traditional neutrality; “He takes the prime minister’s side too quickly.” A prominent Tory MP says: “Heywood is regarded with quite a lot of suspicion by MPs. He’s not avuncular and reassuring in his style. He’s sometimes a little too enthusiastic at finding some contorted way of supporting the government. He’s prepared to come before a select committee and say that black is white. That creates a mistrust. People describe him as a courtier.”

Facebook Twitter Pinterest David Cameron, Jeremy Heywood and Nick Clegg at No 10 Downing Streetin the early days of the coalition Photograph: REX/Shutterstock

Heywood’s critics tend to be foes of Whitehall. And some of their criticisms of him seem incompatible. Can he be both Cameron’s courtier and controller? Too loyal to the government and disloyal? A secret Blairite, as some rightwingers insist, while also the eager servant of Tory governments? Yet politics, especially gossipy high politics, is not always fair or logical; and the fact is that after decades of discreet influence – “I try my best to stay invisible,” he said on his first, belated appearance before a select committee in 2012 – Heywood has become a story. And civil servants are not supposed to be. “He’s not a bad man,” says the Conservative MP David Davis, a frequent adversary. “But he does need to worry that he’s become controversial.” Heywood has become the personification of Whitehall in an era when Whitehall is shrinking and unpopular. Has he reached the zenith of his influence at precisely the wrong moment?

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Heywood was born in the former mill town of Glossop, outside Manchester, in 1961. His mother was an archaeologist and his father was an English teacher at a private Quaker school, Bootham, in York. The Heywoods were not Quakers, but they liked the school’s ethos: it encourages pupils to be precociously confident without being loud, to listen carefully to others, and to resolve conflicts without the heavy-handed application of rules. Heywood became head boy. “He was not a dynamic leader, had no great powers of oratory, but he knew absolutely everything that was going on in school,” says Michael Allen, who taught him history and cricket. “He had quite a good relationship with the school rogues. He was a friend of everyone.”

Heywood applied to Oxford University to study history and economics. “He came back from [his] interview and said he’d mucked it up,” Allen recalls. “The dons had asked him about statistics, which he’d only just started studying. Shortly after the interview, the dons sought me out and said, ‘You’ve got such a clever young man here. We just wanted to keep him off his familiar ground.’” They gave Heywood a scholarship.

His chosen Oxford college, Hertford, was one of the university’s less grandiose, known for its leftwing politics and unusual number of students from state schools. When he started there in 1980, “it was quite a lively time”, remembers a friend and fellow undergraduate. “Thatcher had just been elected. We had friends who were anarchists, post-punks. Jeremy was anti-establishment – or at least very comfortable in the company of lefties. He was a chainsmoker. He pogoed at parties and discos. He went with the anarchists on an overland trip to Pakistan.”

But Heywood is a good compartmentaliser. In 1983 he left Oxford with a first and a place in the fast stream of the civil service. It was then a familiar thing for an ambitious graduate to do: the civil service workforce had hit an all-time peak of 750,000 only six years earlier, and although the Thatcher government was steadily reducing it, there were more than one-and-a-half times as many civil servants as there are now.

After a year as an economist at a relatively new and marginal department, the Health and Safety Executive – for critics of Heywood and Whitehall, a byword for maddening caution and bureaucracy – he moved quickly to one of the civil service’s traditional centres of power: the Treasury. Because it controls the money, writes Hennessy, “The Treasury has a window into every ministry.” In 1984, when Heywood joined, the Treasury was particularly potent, with a self-confident new chancellor, Nigel Lawson, and the British economy finally beginning to boom again after the recessions of the 1970s and early 80s.

Heywood was one of many sharp youngsters in the department. He soon became known for expertly combining technical tasks with more politically delicate work. “I first met Jeremy at the Treasury in 86 or 87,” says the economist Jonathan Portes, who remains a close friend. “He was working as private secretary to [the Treasury minister] Norman Lamont.” Lamont had received a letter from a famous showbiz Tory complaining about their tax bill. Portes had drafted a dismissive reply. “Jeremy thought it was too brusque,” he says. “And Jeremy won.”

Another former Treasury colleague remembers: “Jeremy was the most phenomenal private secretary of his generation. Nobody else has the stamina or the bandwidth. He would run his minister’s life. Sort out which papers they saw. Link them to their department. It’s a job he’s gone on doing, for progressively more important people.”

In 1990, Lamont became chancellor. The following year, he and the slightly gauche new prime minister, John Major, took part in the fraught Maastricht treaty negotiations that created the modern European Union. At one point, Major recalls in his autobiography, the British delegation mislaid the prime minister’s entire bargaining script. “A frantic search took place as I returned to the negotiations without it … Eventually Jeremy Heywood, Norman Lamont’s able private secretary, let out a whoop of delight. He had discovered it among Norman’s papers.”

Not yet 30, Heywood was already a distinct Whitehall presence: even younger-looking than his years, floppy-haired, skinny verging on gaunt, often speaking in a discreet murmur but intimidatingly confident, still a ferocious smoker. Instead of taking public transport to and from work, he would get lifts with colleagues so he could lean out of the window and keep puffing.

Between 1992 and 1993, David Cameron worked with him, as Lamont’s special adviser. According to Cameron’s recent biographers Michael Ashcroft and Isabel Oakeshott, the future prime minister was “in awe” of Heywood. They quote the veteran Tory journalist and Cameron-watcher Bruce Anderson: “People thought [Heywood] lived off coffee and cigarettes. He’d get stopped at airports because he looked like a druggy. [Cameron] thought he was … the cleverest guy he’d ever met.”

He’d get stopped at airports because he looked like a druggy. [Cameron] thought he was … the cleverest guy he’d ever met Bruce Anderson

In 1992, the Treasury’s status and self-esteem were suddenly punctured when Britain was forced to withdraw from the European Exchange Rate Mechanism (ERM), a precursor to the euro. Lamont was sacked as chancellor soon afterwards. But Heywood, less directly associated with the ERM policy, survived, first as private secretary for the new chancellor, Ken Clarke, and then in an even more senior and sensitive Treasury role. In 1994, with the government cutting public spending to pay for the ERM fiasco, – a shrinking of the state that would become almost as severe and prolonged as the current one – Heywood was asked to lead a “fundamental review” of the ministry’s running costs.

He did it with gusto. While the Treasury had been telling other departments to tighten their belts for decades, its own operations, in Heywood’s view, were too unfocused and hierarchical. His report recommended that the Treasury be given “concrete objectives”, such as “delivering permanently low inflation” and “maintaining sound public finances”; that some of its work be handed to “other government departments or the private sector”; and most provocatively of all, that it cut its “senior management posts” by “around 30%”.

Many of Heywood’s colleagues were aghast. “I know of no one here,” an anonymous senior official told the Guardian at the time, “who would dissent from the view that morale is the worst in living memory.” The part of the Treasury where the threatened mandarins worked became known as “the corridor of death”. But many of Heywood’s recommendations were enacted, including the job cuts. He felt that he had made an important contribution to the modernisation of British government. He stayed at the unsettled Treasury for another three years. “Jeremy has a chip of ice in him,” says a friend.

* * *

What Heywood actually believes is the subject of debate among even his closest colleagues and friends. All agree that, unlike many civil servants, he lacks a party-political side, even in the most private social contexts. “He’s the most non-political person I’ve ever met,” says a former Downing Street colleague. “It’s like he had an operation and someone removed the political bit.” Heywood does vote, but only he, and possibly his family, know who for.

Yet, occasionally, off-duty, he lets off steam. An old friend who goes out for dinner with him intermittently says: “He talks about what’s been happening at work that day. To the extent that he gets angry, it’s always been because individuals have been behaving badly ... or incompetence ... or something conspicuously wasteful.” The latter is a longstanding Heywood preoccupation. Someone who worked closely with him for years under Blair says: “He can’t stand waste. He has a pretty laser-like focus on efficiency and rationality. He’s like one of those time and motion men from the 60s: you can imagine him going round with a clipboard.” In the otherwise bland articles and blogs he writes as head of the civil service, about improving working practices and meeting diversity targets, Heywood sometimes describes himself as “a data man”.

In public, he often uses the language of business to explain the work of government: the civil service is “a net exporter of ideas” to foreign bureaucracies; “ministers are customers for our advice”; official reports are “product”. “Jeremy is an expression of the management culture that has gradually taken over Whitehall since the 80s,” says a former Brown adviser. “It’s a free-market conception of statecraft.” Or you could see it as a way of justifying the continued existence of government in an anti-government age.

“You can’t just have grand old Whitehall figures in leather armchairs making promises and policy statements, as you could in the old days,” says Jonathan Powell, Blair’s former chief of staff, who joined the civil service in 1979. “Modern politicians of all parties are desperate for [tangible] things to change on the ground.” It is a climate that suits Heywood. Powell says: “Jeremy is impatient – an attribute of people who get things done.”

Former and current colleagues say that over the decades Heywood has acquired his own policy preoccupations – deregulating the economy, improving British competitiveness, updating the welfare system – and that he prefers working for reforming governments. Richard Reeves, director of strategy for the deputy prime minister Nick Clegg during the coalition’s first two years, says: “Heywood does well under radicals, of the left or the right. He’s a very long way from Sir Humphrey. He wants to use the power of government to change things.”

At the same time, Heywood also believes in order and continuity. In public, he likes to distil the messy, overflowing business of government to pithy lists of achievements and tasks, of official structures and procedures. He talks about crises being “managed down”. He regards much of the media as overexcitable: “There’s a lot of rhetoric in the newspapers,” he told the public administration committee in 2012, “but the business of government goes on.” He speaks quickly but smoothly, with so few hesitations and such a command of detail that it is easy to picture ministers and prime ministers – tired or inexperienced, perhaps, or distracted by party-political matters – listening a little passively, and then doing whatever “Jeremy” suggests.

In 1997, when Labour returned to office after an 18-year absence, Tony Blair quickly summoned Heywood from the Treasury. The two men spoke for a few minutes at No 10, while Blair sat on a sofa and ate an apple. Then the new prime minister hired Heywood as his economic and domestic policy secretary. Despite spending his career so far working for Conservative governments, Heywood was now one of the new premier’s most senior advisers. Or at least, he was in theory. The ambitious Blair government was full of advisers jostling for influence, and in the maze of Downing Street Heywood was given a desk in a different room from Powell, Blair’s key lieutenant. Heywood refused to settle for it; instead, he manoeuvred his way into sharing Powell’s office. Blair’s inner circle were impressed.

Facebook Twitter Pinterest Heywood sits next to Cameron at a cabinet meeting in 2012. Photograph: POOL/AFP/Getty Images

They were also impressed by Heywood’s working style. Polite and unmacho in meetings – useful qualities in a government with too many alpha males – he could be cutting in other contexts. “I would hear him on the phone with Treasury people,” says someone who was with him in Blair’s Downing Street. “They’re so incredibly rude to each other. They have an offensive, not defensive, negotiating style. Jeremy’s very dry, very ascetic, very precise – not like Tony or Gordon at all.”

Blair quickly came to rely on Heywood as a troubleshooter. In 2000, when anti-tax protests at fuel depots began to starve the country of petrol, Powell wrote later, “in desperation” the government “got the operational heads of all the major oil companies and the police … to come into the Cabinet Office, and installed them in a small, chilly office … Jeremy Heywood and I moved in there with them, and we kept them working day and night.” After a week, the protests petered out.

But Heywood’s most valued troubleshooting was internal. With relations increasingly sour between Blair and Brown, go-betweens were required to hold the government together. The chancellor’s emissary was his combative economic adviser, Ed Balls, and initially the prime minister was represented by Powell. But by 1999 Powell had had enough, and Heywood took over the role. He had reservations about Brown. “I remember coming out of a meeting at Chequers in 1998 at which Gordon had been particularly difficult,” says a former Labour spin doctor, “and Jeremy said to me, ‘That man will make a terrible PM!’” But Heywood mostly kept such thoughts to himself, and from his Treasury days he understood the power of a chancellor. The Brownites, in turn, respected Heywood for his Treasury work; had Blair not done so first, the chancellor would have hired him.

For several years, Heywood and Balls met almost daily – often three times daily. Most of the unadvertised meetings took place at the Treasury. But every Tuesday morning, from 8.30 to 9.30, they met on more neutral territory, at Cafe Churchill on Whitehall. The Italian greasy spoon (now gone) sold overpriced, watery cappuccino, but was only yards from both Downing Street and the Treasury, and its interior, only dimly visible from the street, was small enough to deter eavesdroppers.

“Jeremy has this gift for managing to find a way through acrimonious, seemingly impossible situations, picking out what matters most to people, and managing to persuade everyone that they’ve won,” says Portes. Balls came to trust Heywood: first, as a reliable guide to Blair’s thinking; then, increasingly, as a government player in his own right. As Seldon put it in his 2007 book Blair Unbound: “Balls had no respect for Blair as an economist or a thinker, and assumed that he merely took his script from Heywood.” A politician who has worked closely with Heywood says: “To be very good at being a private secretary or cabinet secretary, you have to be very close to the boundary between civil service work and politics, but not step over it. He is very good at that.”

Yet even Heywood’s appetite for Whitehall intrigue is not infinite. During the early 2000s he began to talk to colleagues about taking a sabbatical. One motivation was personal. In 1994, while compiling his unsparing report on the Treasury, he had met and worked with Suzanne Cook, a civil servant who was even more organised than he was. They married in 1997, and in 2002 they had their first child.

The following year, Heywood’s plan to take some time off with his new son turned into something larger: he left Downing Street and the civil service, and joined Morgan Stanley, which went on to hire a succession of senior Labour figures including Powell and Alistair Darling. The hours were shorter, the pay was much better, and after 20 years in Whitehall, Heywood wanted a new environment. His only other break had been a brief secondment in the late 1980s to the British delegation at the International Monetary Fund in Washington DC, a traditional initiation for Treasury high-fliers into the realities of Britain’s place in the world.

At Morgan Stanley, Heywood adjusted to other realities, taking banking exams and acquiring the transatlantic lift to the end of his sentences which often marks out members of the modern British elite. Based in London as an adviser on mergers and acquisitions, and then as co-head of Morgan Stanley’s UK investment banking division, he was excited by the City’s constant hunger for innovations. But he found making money for himself and others less fulfilling than helping run the country. In 2007, after only four years, Brown, now prime minister, persuaded him to come back to Whitehall.

Brown’s young government was struggling. It had hastily called off a general election and was unpopular, divided, derided by the press and a resurgent Conservative opposition. “The No 10 operation was in a total tailspin,” says a Downing Street veteran of the time. Brown was hiding away in his office, working too hard, and hiring too many advisers; power was chaotically scattered through Downing Street.

“Heywood brought a kind of order,” says the veteran. Heywood helped persuade Brown and his key staff to work in the same room, and took a desk right next to the prime minister. Heywood processed Brown’s incessant demands calmly. Heywood delegated. “If you come to a meeting with Jeremy,” says the veteran, “you’ll go away with something to do.”

Even Heywood’s banking experience and contacts proved useful. By leaving the City, he had narrowly avoided direct association with the 2007-8 financial crisis, and instead became a valued part of the government’s efforts to help resolve it, chairing meetings all over Whitehall in the run-up to the G20 summit about the crisis in London in 2009. During the gathering, he told Seldon with rare feeling: “We had a wonderful dinner … Just leaders. No 10 is beautiful on those sorts of evenings. Very intimate. You just sort of see the power in the room, and you just know you’re involved around the edges … of historic moments.”

Facebook Twitter Pinterest Heywood in the centre of the picture leads the applause as Gordon Brown says farewell to 10 Downing Street in 2010. Photograph: Martin Argles/The Guardian

The Brown government stabilised enough to stop the Conservatives winning the 2010 election outright. And the hung parliament presented Heywood with yet more opportunities to be useful and influential. In the Labour peer Andrew Adonis’s well-informed account of the formation of the coalition, 5 Days In May, Heywood appears “in hushed phone conversation at his desk” for most the period, “often with the Queen’s private secretary” about the constitutional complexities of the situation. But once the Tory-Lib Dem coalition crystallised, Heywood was quick to ready himself for his new masters. In the famous photographs of the final moments of the Brown administration, he is wearing a blue tie.

* * *

After the intensity of Brown, the workaholic Heywood took a while to get used to Cameron’s more relaxed approach to being prime minister. “I vividly remember a budget meeting out at Chequers,” says a former coalition adviser. “We were discussing something important, like tax credits, and Cameron tried to bring the conversation to a close, because he wanted lunch. The look on Heywood’s face! You could see the jolt of surprise.”

The adviser continues: “There was less of an intellectual fit between Heywood and Cameron’s people than there had been between him and the Blairites and Brownites. But Cameron came to rely on him. You could see the relief with which he delegated to him.” The inexperienced Tory-Lib Dem coalition also needed his deal-making. During 2011 and 2012, when the parties fell out over whether employment rights should be drastically reduced, in order to (in theory) revive the economy, Heywood suggested a compromise that such rights should only be weakened at startup companies. “No one else had thought of it,” says one of those involved in the discussions. “It was a moment of pure Heywood.”

With his reforming mindset, and his Treasury background, Heywood got on well with the restless new chancellor, George Osborne. But Cameron’s director of strategy, Steve Hilton, was an outspoken critic of Whitehall: he wanted the government to shrink the number of civil servants by three-quarters. At first, Heywood was surprisingly friendly towards his rival. According to Matthew D’Ancona’s history of the coalition, In It Together, “Heywood claimed to agree with much of what [Hilton] stood for and urged him to persist.” Heywood was keen on efficiency, after all. But when Hilton tried to turn his ideas into government policy, Heywood abruptly withdrew his support: telling MPs that Hilton’s plan to gut the civil service, for example, was not “remotely” the government’s approach. Cameron and the Downing Street machine ultimately sided with Heywood: “They liked smooth surfaces and courteous negotiation rather than the deliberate disruption that Hilton favoured,” writes D’Ancona. In 2012 it was announced that Hilton was leaving the government for a university post in America. Shortly afterwards, Heywood was asked by the public administration committee about his Downing Street relationship with Hilton. The cabinet secretary swept a hand across the committee table, fingers outstretched, palm outward. “Steve has now left for California,” he said. “As far as I’m aware.”

Facebook Twitter Pinterest Heywood meeting the Queen in 2015. Photograph: Anthony Devlin/PA Wire/PA Images

Heywood doesn’t enjoy appearing before such committees. He sees the cabinet secretary’s job as essentially private – to be an intimate of the powerful and advise them frankly – and therefore not a very useful object of public scrutiny. But the committees summon him increasingly often, anyway, and question him more and more impatiently, sometimes with open exasperation. His relentlessly level voice, his transatlantic mannerisms, his liking for jargon – “It’s on my dashboard,” he will say, deflatingly, of a potentially juicy controversy – all this can make him seem like a member of the Whitehall establishment, minus the traditional charm; a reined-in and unshowy mandarin for unforgiving times.

“His body language is defensive,” says Flynn, who is on the public administration committee. “He hasn’t built a rapport with us.” In an era of small or nonexistent Westminster majorities, nosy, troublemaking MPs such as Flynn and Davis are increasingly common. Belatedly perhaps, they have woken up to Heywood’s importance. Or they have settled for grilling him as a way of getting at the slippery Cameron. “Part of the role of cabinet secretary,” says a former Heywood colleague, “is to be the PM’s human shield.”

Heywood dislikes media attention even more than select committees. He hates being called “Sir Cover-up” by the Daily Mail. Given all his speeches and committee appearances, given the profusion of online official material about the Cabinet Office’s activities, – which have expanded in recent years, to include everything from the controversial new system of electoral registration to making government procurement more efficient – Heywood considers himself the most transparent cabinet secretary ever.

There is evidence to the contrary. Last September, he said that the Freedom of Information Act had had “some chilling effects” on the operation of government. The publication of the Chilcot report has undeniably been delayed by long negotiations between the inquiry and Heywood about the release of correspondence between Blair and President George W Bush. But it is too simple, and too convenient for the many people in Whitehall, past and present, with things to hide, to see Heywood’s actions in these areas as wholly his own. All cabinet secretaries are sometimes ordered to play Sir Cover-up.

Where Heywood stands out, perhaps, is the stubbornness and ingenuity with which he defends the freedom of action of governments, and of prime ministers in particular. Rather than codes of conduct or fixed Whitehall structures, he murmurs to the select committees, he favours “precedent”, “discretion”, “responsiveness”. This is the traditional clever bodging of British central government. A degree of instability in politics also puts a premium on civil servants, like Heywood, who can offer the opposite.

With the exception of the magazine Civil Service World, Heywood almost never gives on-the-record interviews to reporters, and declined to do so for this article. The more he says in public, he believes, the more journalists will speculate about him, the more manipulations they will attribute to him. But it is almost certainly too late for such reticence: newspaper sketchwriters already converge on his every committee appearance.

The government’s spending cuts, too, are making his life more challenging. State employees he meets on official trips around the country as head of the civil service are sometimes scathing to him about their workplace burdens and conditions. “I’m sure that he’s worried,” says one of his oldest friends. “I don’t think he has a view about whether the cuts are the right thing to do, per se, but if they make the civil service less effective, that would be the opposite of what he has devoted his career to.”

By the next general election, Heywood will be approaching 60. He has three children, and they will all still be teenagers. He is closely involved with them, when his Downing Street duties permit: his list of recreations in Who’s Who reads, “childcare, modern art, cinema, Manchester United”. His wife Suzanne is now a partner at the management consultants McKinsey. She earns a lot more than his £195,000 salary, which is high but not exceptional for a top civil servant – the ultra-competitive Heywood has been known to complain about the disparity – and she is younger. It is possible to imagine him retiring to their large house in south London, with its walk-in wine cellar and the numerous other extensions they have added, which look onto the deep garden. The Heywoods are holders of good, politically eclectic parties.

Portes insists that his friend Jeremy is “still in love with his work. He has this gift for juggling 16 things at once, for keeping it all in his head”. A former close colleague of Heywood says: “There have always been a few people like him in the civil service: very, very big brain capacities, good interlocutors, always in the key meetings – activist civil servants. They always have their supporters, and their detractors. In the 70s, [the head of the civil service] Sir William Armstrong was called ‘the deputy prime minister’.” But Heywood’s ex-colleague does not mention that Armstrong left government after a nervous breakdown.

For now, the most permanent, most potent and most elusive unelected figure in British government can be glimpsed at work more easily than you might imagine. From Horseguards Parade behind Whitehall, after darkness falls, the interior of a particularly fine Victorian office is milkily visible through three net-curtained, first-floor windows. A desk light blazes. A shirtsleeved figure, slightly heavier than in his youth, pads comfortably around, deep into the evening. Sir Jeremy Heywood is working late again.

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• This article was amended on 27 January 2016. An earlier version described Civil Service World as an “in-house journal”. It is an independent magazine, aimed at the civil service.