For seven decades, she bore intimate witness to the shifting of power around the globe. Coming to the throne in the distant era of Stalin's Russia, Elizabeth II reigned through wars cold and hot and through sweeping economic change. She presided over Britain's retreat from empire and its emergence as a modern networked power, but also its struggle to forge a post-Brexit identity and the beginning of a painful reckoning with colonialism. With her goes a unique institutional memory, a reservoir of insights shared with 15 prime ministers.
The relationship between constitutional monarch and elected politician is an odd one - part bowing-and-scraping deference, part curious intimacy. Tony Blair said she was the one person to whom he spoke freely, knowing it wouldn't leak, and the Queen herself once described her function as "a sort of sponge", soaking up confidences. But it also, she added, occasionally involved offering governments a different point of view: 'perhaps they hadn't seen it from that angle'. She was a mistress of soft power, knowing when to project full regal majesty and when to play kindly grandmother, and a unique diplomatic resource. At times she could make Britain's case to a foreign head of state better than any elected politician. (Contrast Emmanuel Macron's spiky relationship with Liz Truss and the genuine warmth of the French president's tribute to the Queen.) Never party political, she was nonetheless core to the body politic, and her relationships with successive prime ministers help tell a story of what Britain has become.
In February 1952, a nation finding its footing in a postwar world acquired a 25-year-old Queen still finding hers. She leaned heavily at first on the counsel of Winston Churchill, half a century her senior; after he retired in 1955, she wrote to him that no other PM could ever "hold the place" of her first. Her second, Sir Anthony Eden, would meanwhile lead the country into national humiliation.
The failed invasion of Egypt now known as the Suez crisis was a hard lesson in wartime statecraft and in the decline of Britain's influence over former colonies. Under Harold Macmillan, who became PM in 1957 and with whom she developed a close rapport, she oversaw the unwinding of empire and the founding of the Commonwealth. But it was her first Labour PM, Harold Wilson, who brought the "wind of change" - Macmillan's phrase, coined to signal the end of Britain's resistance to independence movements - back home.
Wilson's background was humbler than that of his predecessor Sir Alec Douglas-Home, yet he enjoyed a relaxed relationship with the Queen. His was the era of the space race, the "white heat" of technology, and personal liberation: homosexuality decriminalised, abortion legalised, and a swinging 60s culture that risked making the royals look stiff. In 1969, the Queen duly allowed TV cameras into Windsor Castle for an intimate documentary showing the family's human side. The era of mystique and distance was ending.
In 1970, Ted Heath succeeded Wilson, in eerily familiar circumstances: industrial unrest, rocketing inflation, an oil price shock and energy shortages. The Queen wanted to acknowledge these hardships in her 1973 Christmas message, but Heath vetoed it. Might the new king have more leeway this year?
Wilson's short-lived return in 1974 gave way in 1976 to James Callaghan, PM through both the high of the Queen's silver jubilee and the lows of the winter of discontent, but still reportedly a favourite of hers. In 1979 however came a milestone: her first female PM, Margaret Thatcher.
Despite much speculation about the two women's personal differences - Thatcher clearly didn't enjoy trudging across grouse moors at Balmoral - the real tension was over policy. Thatcher's reluctance to increase sanctions against an apartheid-era South Africa enraged Commonwealth leaders, and the Queen reportedly sided with the latter.
Thatcher's downfall in 1990 saw more bitter political infighting over Europe under John Major, and a sterling crisis culminating in the Black Wednesday crash. But the Queen appreciated Major's support during her own "annus horribilis" of 1992, with Prince Charles's marriage unravelling and some asking whether the monarchy could survive. Five years later, the death of Diana, Princess of Wales, brought those questions rushing back.
A new PM, Tony Blair, deftly caught the mood of grief for the "people's princess", but the Queen came across as too remote, and relations between No 10 and the Palace deteriorated.
Rumours spread that the Queen was unhappy with New Labour's plans to ban foxhunting and reform the House of Lords. Things weren't much easier after Gordon Brown succeeded Blair in 2007, although the Queen was keenly interested in the banking crisis, asking pointed questions about failures in economic forecasting while visiting the London School of Economics. It was the constitutional upheaval under David Cameron, however, that really tested relations between monarch and state.
Things began well, with a 2011 visit to Ireland in which the Queen candidly acknowledged sufferings under British rule. She gamely joined in a James Bond skit at the following year's Olympic opening ceremony, suggesting a monarch and country at ease with themselves. Two years later, however, came the Scottish independence referendum, after which Cameron was overheard telling how she had "purred with pleasure" at the result - a serious breach of her political neutrality. Worse still, before the Brexit referendum, an unnamed minister told the Sun she supported Leave. By 2016, when Theresa May succeeded Cameron, the country was bitterly divided.
Seeking to carve a new post-Brexit role for Britain in the world, May leaned heavily on royal soft power. The then Duke and Duchess of Cambridge led a charm offensive in European capitals, and the Queen's presence helped smooth a difficult 2019 state visit from Donald Trump, who craved her approval. When a politically floundering May was ousted that summer by Boris Johnson, however, something cracked.
Attempting to force his Brexit deal through, Johnson embroiled the Queen in a prorogation of parliament subsequently deemed unlawful. She grieved alone in a socially distanced pew at her beloved husband's funeral the day after Johnson's aides had thrown a raucous lockdown-busting party. The Queen's dutiful willingness to suffer the privations of a pandemic alongside her people contrasted painfully with what now passed for political leadership.
Yet the monarchy had its own troubles in this period, from Prince Andrew's public disgrace to allegations of royal racism in the wake of Prince Harry's break with the family. This spring's ill-judged Caribbean tour by the Cambridges, meanwhile, stirred up demands for reparations for slavery, anger over the Windrush immigration scandal (which erupted on May's watch) and talk of Jamaica becoming a republic. Suddenly, history appeared to be catching up with a monarchy that had long outrun it.
The dying Queen's final public act was the kissing of hands with Liz Truss, sealing one last orderly transfer of political power. The circle is unbroken; the line continues under a new prime minister and king. But who knows where, in seven decades' time, it will lead?