Uneasy lies the head that writes The Crown, I imagine.
In undertaking to dramatise the entire story of the Queen from the 1920s to the early 21st century, the author, Peter Morgan, set himself a huge and controversial task. He understood from the first that the narrative had to encompass both public and private.
That is why it is called The Crown, not The Queen. Living through the conflict between the two is the destiny of dynasty. Successfully doing so is the underlying story of Elizabeth II.
The narrative therefore has to portray the Queen's relationships not only with her family, but with other public figures – above all, her prime ministers.
Her first prime minister, Winston Churchill, was, as it were, grandfather to the very young Queen. Her third, Harold Macmillan, was paternal.
In the new fourth series, the Queen has been on the throne for nearly 30 years and is on to her eighth PM. For the first time, she finds herself with one of the same age – which was eventually to be expected – and of the same sex, which was not.
Britain was then a man's world, yet both the head of state (born 1926) and the head of government, Margaret Thatcher (born 1925), were women. The world had never seen anything like it.
Perhaps neither woman wholly welcomed it, since both seemed to prefer the company of men. "I have found women in general not to be suited to high office," Morgan has Thatcher say to the Queen as they discuss her first, all-male Cabinet.
The Queen's facial reaction suggests she is amused that Thatcher doesn't see the irony, but also that she might agree with her.
When writing my biography of Thatcher, I came across the earliest known vignette of the two in the same place. In 1949, Margaret Roberts, aged 23, was taken to the 2000 Guineas at Newmarket by her then boyfriend (not Denis).
The future Queen was also present. Bossily hijacking her boyfriend's diary, Margaret wrote in it, "I saw Princess Elizabeth, and she saw me!" From the very first, there was a note of excitement and of comparison, even of competition.
Peter Morgan makes a similar point in this series. As the 21-year-old Princess broadcasts her famous vow from South Africa ("the whole of my life, whether it be long or short…"), the camera sweeps across the world, showing audiences of the poor in India, Africa etc and ending up with Margaret, the busy Conservative student at Oxford. She is seen listening reverently.
Arriving for her first audience in Buckingham Palace in 1979, she is reverent still. Gillian Anderson, as Thatcher, captures the careful precision of her dress, hair and voice and the exaggerated depth of her curtsy, which made courtiers laugh.
This is the only convincing performance I have seen of Thatcher as Prime Minister (Meryl Streep's star turn in The Iron Lady was of her old age: she was more uncertain acting her in her pomp).
In her appearance and manner at the weekly audience, Thatcher was demonstrating a combination of respect and social unease. As the first woman prime minister, she had unprecedented problems about what to wear. She could not ask – it is against the unwritten rules – what the Queen would be wearing. She feared upstaging or accidentally imitating her sovereign's wardrobe (the latter did occasionally happen).
As the daughter of a provincial grocer, she also worried about how to comport herself in the royal presence. While she was in office, this worry never went away. Although in politics almost a revolutionary – something The Crown portrays well – she was also a stickler for "correct" form. Only in Thatcher's retirement did everything become surprisingly cosy between the two women. The Queen paid her the unusual honour of attending her 80th birthday party. They moved chattily around the room side by side, grandmothers together.
The second episode, The Balmoral Test, is about that initial unease. Denis and Margaret arrive for their first prime ministerial stay at the Queen's Deeside castle and do everything "wrong". Dressed for dinner, they enter the drawing room at 6pm, only to find the merry royal party recently down from the hill and still having tea.
The following day, Prime Minister and Queen accompany the stalking, Thatcher in her London suit. As they cross the glen, the Queen tells her that the suit's conspicuous blue will make the stalked stag see her. After vain struggles in the squelching peat, she is sent home to change.
This improbable scene shows the Queen being actively discourteous, which is surely wrong. At the Braemar games, Thatcher protests to Denis: "I'm struggling to find any redeeming features in these people at all."
That is similarly overexplicit. But the broad impression of the visit has the ring of truth – Mrs T as a fish out of water, and laughed at for it. Her real-life way of expressing her desire to get back to her beloved work was less overt: at seven on the morning of departure from Balmoral, she was always ready to be off in time to avoid another slow, full Scottish breakfast.
Once the narrative turns to political events, the details go haywire. Small examples: her then chancellor, Geoffrey Howe, never tried to impede the Falklands War and did not attend the key meeting where it was decided to send in the task force; her most important private secretary, Charles Powell, was not working for her at that time; her son Mark was not lost (and found) in the desert just as the Falklands were invaded.
I mention such inaccuracies, however, only to accept Morgan's view that the drama should not be tyrannised by fact, but seen as "an act of imagination". On the whole, The Crown manages this problem well.
Alteration of the facts becomes serious only when grossly unfair to individuals or when it actually impedes the narrative or characterisation. Audiences do, after all, believe that what they are watching is essentially true. If they sense it is not, trust in the drama frays.
There are several such significant fact-skewings in series four. I single out only one.
Thatcher wins the first ballot in the leadership challenge of 1990 by only four votes. Colleagues say she must go. No, she tells Denis excitedly, "I still have one card to play." Off she rushes to the palace and begs the Queen to dissolve Parliament to save her from resignation. This is factual nonsense.
Worse, it undermines the character the series has built up. Thatcher was certainly, as Gillian Anderson well portrays, a woman of great ardour, but she was also respectful of constitutional rules. So, of course, was the Queen.
The story suddenly lurches. It is incredible, both dramatically and historically. The Queen would never intervene to save the neck of a prime minister who was losing her party's support, and Thatcher would never have thought of asking her to do so. Everything suddenly turns silly.
Luckily, the drama then rescues itself. The ensuing scene when the Queen thanks the departing Thatcher for everything she has done in office by personally awarding her the Order of Merit and pinning it on her breast is moving. The ex-prime minister's heart is too full for her to speak.
All dramatic presentations of the Queen and Thatcher have a similar problem, I think. The authors naturally want striking words to be exchanged, so they make both women say too much. The truth is more typically, interestingly British – that each felt somewhat constrained in the other's company.
Thatcher was never, ever rude to the Queen (at one point in The Crown she is shown trying to leave an audience early because she is so cross: unthinkable) or even about her. As for the Queen, both her personal character and her constitutional role mean she rarely tackles things head-on.
Olivia Colman, acting very watchably but not very Queenishly, lacks the inscrutable mask of regality that is the Queen's stock-in-trade. The script sometimes makes this mistake, too. During Thatcher's fall, the Queen bursts out at her: "Perhaps the time has come for you to try to do nothing, for once." Such words do not fit the restrained Elizabeth II we have come to know over so many years and episodes – the woman whose favourite three real-life words of rebuke are, "Are you sure?"
A related problem is the question of taking sides over such a controversial person as Thatcher. Morgan tells me he is at pains to avoid anything didactic or politicised. "I am an equal opportunities writer," he jokes, open to an audience of all views. He says he is offering an "invitation" to the show's vast global audience to engage in the history themselves, rather than preaching it to them. I believe him, but there are times when the old anti-Thatcher lines are unconvincingly given the royal seal of approval.
Take the strange case of Michael Fagan, the eccentric drifter, who somehow got into the Queen's bedroom in Buckingham Palace in 1982 and talked to her as she lay nervously in bed. The Crown has him regaling her with a diatribe against Thatcher's Britain which sounds like one of Neil Kinnock's windy speeches.
But when he is later dismissed as mentally deranged, she disagrees. He is deranged "only in the best sense," says Her Majesty admiringly, "like Lear's fool." That is not the authentic voice of cautious, plain-thinking Elizabeth Windsor, who is well known for her lack of interest in Shakespeare, and is hardly likely to accept a version of Thatcher from a strange interloper in the bedchamber.
But I return to Morgan's "act of imagination". At the core of The Crown's portrayal of the Queen/Thatcher relationship is its odd, interesting parallelism. Two mothers, who both dote on sons (Andrew, Mark) whom the rest of the world tend to find underwhelming; two women who share seriousness, hard work, Christianity and patriotism and have grown up together in years, though apart in milieu; and two leaders whose roles and characters lead them to respond to national problems in completely different ways – the Queen quietly seeking continuity, Thatcher pushing ceaselessly for change. This is a gripping story of woman-power, played out by two middle-aged ladies who never answered to the name of feminist.
•The fourth series of The Crown will be on Netflix streams from Sunday.