It was​ in Charles Dickens’s upstairs sitting room that I met the future king of England. The Duchess of Cornwall was wearing a red paisley silk coat and dress by Anna Valentine. I know that because I was peeping out of the window and heard a lady from the Daily Mail say so into her mobile phone while she stalked the pavement outside. We were about to commemorate the 200th anniversary of Dickens’s birth, and of course the royals were late, and we, the curtain twitchers of Bloomsbury, had been working overtime. As the royal correspondents like to say, there was a definite buzz when the couple arrived, and we assumed our positions, waiting like Victorian waxworks for the buzz to turn into a creak on the stairs.

My friend Gillian Anderson (she had asked me to accompany her) got the giggles and had to be calmed. But she was completely composed by the time the royal couple entered the room, walking slowly, looking completely and utterly baffled by the spectacle of being themselves. If most things in your life are a photo opportunity, it must be hard to find the leisure to be genuinely interested, and this problem was very much Camilla’s when she was handed a Dickens first edition. She couldn’t see it without her glasses but she didn’t want to be photographed wearing them. ‘I’ll just pretend to read it,’ she said, and the ghost of Charles Dickens, great lover of charades, was heard to laugh in that part of the ether where life is much stranger than fiction. Charles sat in an armchair, his wife sat beside him, and the actress read them a few pages of Great Expectations, which they seemed to like well enough. ‘Oh, what fun it is to be read to,’ Prince Charles said at the end. ‘It’s like bedtime.’

‘I can tuck you in too, if you like,’ Gillian Anderson said.

‘Yes, please,’ he said. At which point, the smile disappeared from the duchess’s face and they went downstairs to a waiting Land Rover. Gillian and I were ushered into a car behind them and lights started flashing as we headed to Westminster Abbey. Of all the colourful situations I have endured at the behest of the LRB – begging on the streets, sloshing through New Orleans, running with child jihadis, being Ronald Pinn – none has been more ludicrous than the experience of racing through London’s traffic lights as part of a royal motorcade. When we arrived, the prince seemed more ruddy-faced and self-alienated than before, and I wondered if words had been exchanged, but I have no evidence and can only say that we walked in procession to Poets’ Corner, surrounded by a very packed house of the clearly-having-been-kept-waiting. Forrest Gump, eat your heart out. My phone was buzzing in my pocket and I later found texts from writers in the congregation, friends of mine, basically saying ‘what the fuck is going on?’

In the way that chefs are allowed to be greedy and beauticians vain, princelings are entitled to special treatment. What’s the point of having a royal family if they’re going to be like everybody else? (Brave 1980s attempts at normality failed, and brought us Sarah Ferguson, the commoner’s commoner.) So, Prince Charles, his whole life, has been accused of wastefulness, self-importance and fastidious idleness, and any book that claimed otherwise would be considered a letdown. The new biography by Catherine Mayer, Charles: The Heart of a King (W.H. Allen, £20), begins by reminding people of an earlier claim, made by Jeremy Paxman, that Charles regularly instructs his cook to boil seven eggs each morning in the hope of getting a soft one. But then quickly quotes a former private secretary who says this can’t be true, because Charles hates waste. This is Mayer’s method, a method you might recognise, that of the ‘good friend’ who likes to tell a story against you, only to say with their next breath how improbable it is, the friend appearing to earn their loyalty stripes while undermining you.

Such blackguards thrive in royal circles. And there is nothing more bitchy, more toadying, more venal, and less meaningfully journalistic, than the intimates known as royal correspondents. Contra Diana, who cultivated them (her inner circle of hacks), Charles has always preferred actors or intellectual flunkies with a degree in agriculture. This has been good for his soul, fair-to-middling for his ego, and disastrous for his public relations. It’s true the prince once cultivated Jonathan Dimbleby, whom he somehow imagined to be the closest thing, in human form, to an Exocet missile, but it turned out that Mr Dimbleby, the erstwhile president of the Soil Association, was a damp squib. ‘Not all the water in the rough rude sea can wash the balm from an anointed king,’ says Richard II, but the problem has always been that Charles is, as it were, pre-anointed, and being The Boss without being The Boss has been the condition of his adult life. His task, in the shadow of his mother, has been to try to preserve himself in a state of near infallibility, and he has struggled with the fact that managing his image is the only real job he has.

Now enter Catherine Mayer, to find the prince vulnerable. He treats her to a couple of suppers at Dumfries House, and tries to coddle her, but this is a man who lacks the confidence to fashion his own profile or to think outside the royal box – as a thinker, he’s still conjuring with the late Jungian blether of Laurens van der Post – and Mayer turns to gossip and simmering insider resentments to help her fashion a more vivid picture. Clarence House, his London residence, is apparently known as Wolf Hall, where no opinion can be held independently, and dark manipulations fill the corridors. His courtiers call the monied individuals whom Charles brings to supper ‘Bond villains’. He hangs his watercolours beside Old Masters. He is generally ovine in nature, preferring sheep to people. ‘We talk a lot about the guilt of privilege,’ his friend Emma Thompson is quoted as saying. ‘Sometimes I think he’s driven by guilt.’ The new biographer has a lot of feeling for her subject, if that’s a permissible word. In her wicked way, she wants to set him up as an Average Joe, then slay the inner beast of entitlement. It’s a hard job, and maybe not the fairest one, to feign surprise, and a little indignation, when the Average Joe turns out to be His Royal Highness Prince Charles Philip Arthur George, Prince of Wales, KG, KT, GCB, OM, AK, QSO, PC, ADC, Earl of Chester, Duke of Cornwall, Duke of Rothesay, Earl of Carrick, Baron of Renfrew, Lord of the Isles, and Prince and Great Steward of Scotland. ‘Yes, yes,’ the royal biographer appears to mutter, ‘but does he wash his own cups?’

Repeatedly, the charge sheet is written out, and the paper crumpled up. But treason often comes with a shameless manifesto, and Mayer’s might be the best yet. ‘This biography is written in the belief that concealment neither benefits the institution whose future relies on him nor serves the needs of the democracies of which it is a constitutional pillar. If the narrative often reads like comedy, that is because Charles’s life serves up comedy at many turns … This book attempts to bring clarity to both sides of the debate … he deserves to be understood.’ The more serious side of the charge sheet, if you want to get into it, concerns Charles’s hobby of writing letters to government ministers in an attempt to influence policy. In former times, he might have been forced to mount the scaffold outside the Banqueting House in Whitehall, but in our time he might just be forced to face a legal challenge from the Guardian, which wants the letters published. I can see why they would and he was foolish to write them.

It’s hard to be king when you’re the knave of hearts. More than his political interference, more than the legend of the ‘monstrous carbuncle’, more than Camillagate, and much more than the recent news of courtiers complaining of dark dealings in Clarence House, it is Charles’s marriage to Diana that still snaps at his reputation, as if his greatest role so far has not been king-in-waiting but the older man who took a fairytale princess and wrecked a national illusion. In the era of victimhood, to be the ‘cold fish’, as Mayer puts it, ‘whose cheating drove the princess to an eating disorder and suicide attempts’, is a crime for which he might never be able to atone. The royal biography industry can only seek to give a new spin to these old tales – tales that were never entirely real in the first place. Royal life has long since been painted over with fictions, and our news agenda is almost proud of its constant hunger for more. ‘Why are we so attached to the severities of the past?’ Hilary Mantel writes in Wolf Hall. ‘Why are we so proud of having endured our fathers and our mothers, the fireless days and the meatless days, the cold winters and the sharp tongues? It’s not as if we had a choice.’