For prime ministers, discretion is a rare commodity.
There are few people whose lives and words are scrutinised as closely and for whom secrecy is so hard to obtain.
Throughout her long reign, the Queen met with 15 prime ministers in a setting otherwise rare to come across in government: total secrecy.
The Queen was constitutionally forbidden from interfering in political matters beyond her limited ceremonial roles but the government has a duty to keep the monarch informed of government business.
Her reputation for keeping a secret is without rival and those audiences served as a sounding board for politicians of all stripes.
They would all find an engaged and knowledgeable listener sitting opposite them, one who took a fierce interest in the business of government.
The matter of who the Queen’s favourite prime minister was is about as closely guarded a secret as the issues discussed in the meetings.
Her affection for Winston Churchill and Harold Wilson is well-documented, as are the tensions she had with Margaret Thatcher and Tony Blair – but what about the rest?
Metro.co.uk has looked back at Downing Street-Buckingham Palace relations under every prime minister during the Queen’s reign.
Unsurprisingly, she held a deep affection and respect for Churchill, her first prime minister and a figure who had been in her life for several years already.
He had been the prime minister who, together with her father, had fortified the nation’s resolve during the Second World War and he would have been a familiar figure to her by the time she took to the throne in 1952, a year into his second spell as prime minister.
Follow Metro.co.uk's live blog for the latest updates, and sign Metro.co.uk's book of condolence to Her Majesty here.
By that point, Churchill was arguably past the peak of his political powers – he had been dramatically voted out in 1945 and narrowly defeated in 1950 – but the Queen’s admiration for him was beyond doubt.
He was much older but would have had sympathy for the position the Queen found herself in at a young age. He was first elected to parliament at 25, the same as the Queen was when she ascended to the throne.
In 1928, he said of a young Elizabeth that she had an ‘authority & reflectiveness astonishing in an infant’.
A romantic and staunch monarchist, he would later tutor the young monarch in the constitution and came to view her almost as a daughter.
When he relinquished power in 1955, the Queen wrote of him that no other leader ‘will ever for me be able to hold the place of my first prime minister, to whom both my husband and I owe so much and for whose wise guidance during the early years of my reign I shall always be so profoundly grateful’.
She had a far less warm relationship with his successor, Anthony Eden, a man who wasn’t instinctively a monarchist in the same way as Churchill and not particularly interested in nurturing good relations with the crown.
There was reportedly a distance between the pair but their encounters lasted less than two years before the Suez Crisis upended Eden’s government.
Some historians hold that the Queen was kept in the dark about the ill-fated military escapade in Egypt but that is disputed.
What is not is that the Queen would have been profoundly disappointed to see Britain’s standing in the world weakened and her Commonwealth rocked, especially if her views had not been sought.
There was little time to form much of a relationship with Sir Alec Douglas-Home, who served for just 363 days. At this stage, the Conservative Party did not have a formal way of choosing a new leader so the Queen was asked to appoint a new prime minister on the advice of a small group of Tory grandees following Eden’s resignation.
This was the last true entanglement of the crown in parliamentary politics and was described by one royal biographer as the biggest mistake of her reign because the Queen had appeared to side with a faction within the party.
Little is known of their relationship but Douglas-Home did play a small role in royal history, ensuring that post boxes in Scotland were emblazoned simply with a crown rather than Elizabeth II’s royal insignia to appease those who pointed out Elizabeth I had never ruled Scotland.
She famously got on like a house on fire with Harold Wilson, an unlikely match, after his 1970 election. By today’s standards, this pipe-smoking, Oxford-educated economics lecturer may not seem particularly cutting edge, but at the time he represented a new type of politician.
Mr Wilson, the first Labour prime minister of the Queen’s reign, came from a modest background, spoke with a Yorkshire accent and struck a far more casual tone than his hyper-formal, mostly aristocratic predecessors.
He was older than the Queen but much closer in age than some previous prime ministers had been (10 years separated the Queen and Mr Wilson, compared to 52 years with Winston Churchill).
Wilson’s style, a forerunner of the type of politician we take for granted today, influenced the relaxed nature of their weekly meetings, with some royal biographers speculating that the Queen was able to learn about a section of the country she’d been somewhat shielded from in her privileged life.
They would reportedly chat openly and run over the time allotted for their audiences, occasionally sharing a drink and with Mr Wilson even permitted to smoke. He was apparently so proud of their relationship he would later keep a photograph of them together in his wallet.
Wilson was replaced for four years by Edward Heath, although would return again between 1970-72. Heath was a Tory much more in the vein of the previous prime minister’s during the Queen’s reign up to that point and she is generally held to have been less close to him than Wilson.
Unlike the rest of the PM’s, unguarded video footage of the pair chatting exists which gives an insight into the nature of their relationship and suggests a familiarity but not exactly an overabundance of respect.
During a G7 summit in 1991, the BBC filmed the Queen discussing the feasibility of a visit for Western leaders to Saddam Hussein in Baghdad with then-US secretary of state James Baker and a retired Heath.
When he interrupted the Queen, who demonstrably knew her stuff on the situation in the Middle East, to tell him he had visited Iraq, she quipped: ‘I know you did, but you are expendable now’.
The second Labour prime minister of her reign was James Callaghan, who was cut from the same cloth as Harold Wilson. It’s generally held they had a close, casual relationship similar to the previous red inhabitant of Number 10, but he would later say of the Queen: ‘What one gets is friendliness but not friendship.’
The relationship between the Queen and Margaret Thatcher is perhaps the most discussed of her reign, thanks in no small part to the Netflix series The Crown.
Their relationship was the first time the public had good reasons to believe there was tension between Buckingham Palace and Downing Street. A private disagreement between the pair over sanctions on apartheid era South Africa became public, a rare breach of royal protocol which was viewed as a scandal at the time.
Thatcher always denied any tension but, given they were similar ages and both highly influential female figures in the country, it’s not hard to see where a sense of rivalry might have stemmed from.
Several biographers have claimed there was no love lost between the pair but the Queen went out of her way to honour Thatcher when she retired and attended her funeral, the first of a former prime minister she had gone to since the death of Churchill.
The depth of affection towards Thatcher’s Tory successor within the Royal Family is underestimated.
His audiences with the Queen coincided with some of the darkest days of her reign, including the ‘annus horribilis’ of 1992, and more so than ever the audiences may have been as much about the problems of the firm as opposed to the government.
He had been voted out a few months before the death of the Princess of Wales in 1997 but Major was appointed legal guardian to William and Harry, helping to represent them in administrative matters arising from the tragedy.
Major is still considered a close part of the royal circle and was notably the only politician invited to Harry’s wedding to Meghan Markle.
Tony Blair’s relationship with the Queen has become the stuff of myth thanks to the film The Queen.
He personally put pressure on the monarchy to publicly display their emotional response to the death of Princess Diana after the muted reaction from Buckingham Palace angered the public.
Blair said in his autobiography that he found the Queen ‘direct’ but looked forward to the sessions, saying she had an ‘immense fund of insight and wisdom to offer’.
He also said she was scrupulous at avoiding giving a political opinion and added that she ‘presumably’ has politics but he had no idea what they were after a decade of meetings.
Gordon Brown was tasked with keeping the Queen abreast of a series of crises during his short tenure, not least the global financial crisis.
It’s unclear how convivial their relationship was and Brown has remained tight-lipped on the subject. However, Buckingham Palace was accused of snubbing him and Blair when they were not invited to the royal wedding in 2011.
It’s safe to assume these relationships were more professional than they had been with previous Labour prime ministers.
The UK returned to Tory government in 2010 with a prime minister from similar social stock to the early prime minister’s of the Queen’s reign.
But David Cameron managed to put his foot in it on a couple of occasions with the Queen, leading to word from Buckingham Palace he had caused ‘displeasure’.
He was caught on camera revealing the Queen had ‘purred down the line’ when she was told Scotland had rejected independence and would reveal after he left Downing Street that he had asked the Queen to ‘raise an eyebrow’ during the campaign.
Both were considered betrayals of the cast iron discretion the Queen had offered her prime ministers so it’s not beyond the realms of possibility that he wasn’t exactly a favourite.
Theresa May was the second female prime minister of her reign and is said to have had a warm relationship with the Queen (typified by a funny story she revealed in her Commons tribute following the monarch’s death).
ITV’s royal editor Chris Ship said he had heard people in the royal circle ‘speak with admiration for the level of hard work and many hours of negotiation Theresa May has invested in her role over the last three years’.
Little is known of the relationship between Boris Johnson and the Queen, whose in-person audiences have been limited by Covid-19.
But there was excruciating embarrassment for Mr Johnson when it emerged Downing Street staff had held a party on the eve of Prince Philip’s funeral, a rule breach he personally apologised to her for.
It’s also probably safe to assume she wouldn’t have been impressed by attempts from some in the Vote Leave camp to claim the Queen was a closet Brexiteer.
Liz Truss was the last of the 15 prime ministers the Queen saw in her reign, meeting with her at Balmoral two days before she died to be formally invited to form a government.
With a fire roaring behind her, the 96-year-old leaned on her walking stick and stood for the final picture ever taken of her.
Visibly frailer than just a few months before, she rose to smile and shake hands with the prime minister and carried out the last major constitutional duty of her life.
Just 48 hours later, Ms Truss was offering her condolences to King Charles.
Get in touch with our news team by emailing us at webnews@metro.co.uk.
For more stories like this, check our news page.