Sarah Vine: King Charles has a hard act to follow, taking place of late Queen Elizabeth II

There were many reasons our late Queen was held in such deep affection and so widely admired, but one of them, I think, was her quiet humility.

For all her titles, she was the opposite of entitled. We saw that not only in her attitude towards her duties, but in her personal habits too. She was thrifty, she abhorred waste, she was not afraid to get her hands dirty.

She judged people by their actions, not their status, and was just as comfortable spending her days with the daughter of a docker — Angela Kelly, her dresser and confidante in later years — as any high-born duchess.

The Crown was hers to inherit; but she worked tirelessly to prove that she was worthy of wearing it.

Whatever the privileges of her position, she never took any of it for granted.

All this is a very hard act to follow — and yet it is the task that faces her successor, King Charles.

For now, of course, he must rest, having lived through a deeply tiring, traumatic and emotionally charged few days. But if he is to guide the monarchy successfully into its next chapter, he must show that he understands that the true mark of a monarch is determined not by the symbols and trappings of power, but by concrete actions.

Already we have seen just how much the King is capable of. A whirlwind tour of the country, procession after procession, addressing the nation, solemn speech after solemn speech, endless walkabouts, greeting of dignitaries, shaking of hands and, of course, the hardest thing of all: standing vigil at his mother’s coffin before finally laying her to rest and assuming the mantle of power himself.

There aren’t many 73-year-olds who could endure such a punishing schedule, let alone while dealing with the huge emotional turmoil of losing someone who was not only a beloved parent but also an icon against which he will inevitably be judged. I hope Camilla’s got him on the cod liver oil.

But the real test will be over the next few weeks and months, as he settles into his new role and the character of his reign begins to take shape. There are many pressing issues that await his attention, and he can’t just dismiss them with a grimace and a petulant wave of his hand, as he did with that pesky pen last week.

First and foremost is the question of the Duke and Duchess of Sussex. They just about fell into line for the sake of the Queen’s memory, but it still feels more like a temporary truce than a lasting peace.

Certainly nothing fundamental seems to have changed in the demeanour of Prince Harry, especially after he made it known how upset he was about having the Queen’s initials removed from his Army uniform as he stood vigil over his grandmother’s coffin.

It won’t be long before he and Meghan are back in California, and without the benign influence of his grandmother to keep him in check, it could well be all-out war. Unless, that is, the King can persuade Harry to abandon his plans for a tell-all book and find other ways of earning a living that don’t involve trading off his and Meghan’s so-called “misery”.

Prince Andrew, too, is a problem — although perhaps less so, since he doesn’t have a vast social media following and an army of adoring fans to egg him on.

But there are difficulties beyond the immediate family, too.

Britons are facing a winter of hardship, with soaring energy prices and increases in the cost of living.

The late Queen, with her two-bar electric heater at Balmoral Castle, would have had no trouble resisting criticism of the royal lifestyle; this may be trickier for King Charles. Especially given his pending coronation, which is likely to take place next northern hemisphere spring or early summer. Already there are questions about whether, given everything, a full-blown state occasion is appropriate.

The optics of opulence have rarely been harder to justify, and even a pared-down ceremony is likely to draw criticism, especially from those who see the death of the Queen as an opportunity to undermine the monarchy.

Personally, I think if you’re going to have a coronation, it should be bells and whistles. After all, Britain is a monarchy, and that’s what monarchies do.

That said, if I were King Charles, I would not rush to book the abbey. I would give myself a bit of time, a period of reflection, and focus on getting my house in order first.

I would begin to put in place measures to slim down the monarchy; deal with the more pressing matters at hand; and generally work on building allies and goodwill.

That way, when the coronation finally happens, it will feel entirely justified: a well-deserved celebration of a great British institution — and not, as its enemies will doubtless try to frame it, an empty extravagance we can ill-afford.