Whatever happens next to Andrew Mountbatten-Windsor, this much is certain: he can no longer remain in the royal line of succession.

Even if all the allegations against him turn out to be unfounded, even if he is exonerated of every last suggestion of wrongdoing, the one thing he has proved beyond all reasonable doubt is that he is neither morally nor temperamentally fit to be king.

Quite what he is fit for is unclear. What can a man who has lived his entire 66 years inside a bubble of entitlement and privilege do when that bubble bursts?

Part of me genuinely feels for him. That photograph of him returning to Sandringham after 11 hours in police custody shows the face of a man in utter despair. However much he may or may not have brought it upon himself, however much he may or may not deserve his fall from grace, there is no doubt the man is in pain. But the fact remains that he can never be king.

You cannot have someone who has lied through his teeth to the British public, who maintained a close friendship with a convicted paedophile, enjoyed his hospitality and returned the favour, who allegedly divulged sensitive government information and turned a blind eye to what appears to have been blatant sex trafficking, who for the past 15 years has had a toxic cloud of suspicion hanging over him, anywhere near the British throne.

Even if nothing is ever proven, and he remains a free man, a whiff of corruption, perversion and general grubby behaviour utterly unbecoming of a member of the British Royal Family will always cling to him.

Distasteful images of Andrew leering on all fours over a prone young woman, or passing a ball in the shape of a woman’s breast to an unknown toddler, will not fade from memory. They are seared on the nation’s consciousness.

Photographs of Ghislaine Maxwell, Harvey Weinstein and Jeffrey Epstein (one dead, the other two convicted sex offenders) grinning at his daughter’s 18th birthday party will not be quickly forgotten, and neither will those of him strolling in Central Park with his ‘friend’ (‘we are in this together’) or smiling at a young woman in the doorway of Epstein’s New York home.

Part of me genuinely feels for him, writes Sarah Vine. That photograph of him returning to Sandringham after 11 hours in police custody shows the face of a man in utter despair

What can a man who has lived his entire 66 years inside a bubble of entitlement and privilege do when that bubble bursts?

Those images are indelible. They do not prove culpability, but they do paint a picture of the character of the man. As does the famous photograph of him with his arm around the late Virginia Giuffre, a woman he denied ever even knowing in an interview which later turned out to be laced with lies. A woman he paid millions to in return for her silence, but whose ghost now haunts him and all others embroiled in this sordid saga.

Given all that, there is just no way he can remain eighth in line to the throne. It’s not a question of royal protocol; it’s a question of propriety.

Can you imagine Andrew seated on the Coronation Chair in Westminster Abbey? Uttering the solemn oath of office, being anointed with holy oil by the Archbishop, holding sceptre and orb and wielding the sword of justice? It’s just unthinkable.

There is no way St Edward’s crown can ever rest on this man’s head. That day would spell the end of the British monarchy.

Let’s face it, we’ve had some shockers over the centuries. Bad King John, whose thirst for money made Sarah Ferguson look coy; Edward II, who sold royal patronage to the highest bidder and was eventually deposed by Parliament and, legend has it, a strategically placed hot poker; Ethelred the Unready – history is littered with them, all monarchs who proved that the crown doesn’t necessarily make the king. But this is not the Dark Ages (probably just as well from Andrew’s point of view, given the punishment for treason). He can’t just send his enemies to the Tower and tell the servants to spit-roast another hog.

A modern monarchy in an age of social media could not survive someone with a reputation as tarnished as his ascending the throne. It would lead to a public outcry, and very possibly a revolution.

That is why he must be removed from the line of succession. It will require an Act of Parliament, but it’s also an act of common sense, not to mention self-preservation.

The King has already gone some way to mitigating the damage by removing Andrew’s titles and turfing him out of Royal Lodge. That was the right thing to do: Again, even if he is found not guilty of any specific charges, Andrew’s general conduct has been so unbecoming he left his brother with no choice.

But if – God forbid – a terrible disaster should befall the Royal Family and Andrew somehow ended up in the hot seat, that would be the end.

For that to happen really would take a catastrophe. Not only would his brother have to shuffle off this mortal coil, but all the Waleses and the Sussexes too.

It’s an extremely unlikely scenario. I suppose it is theoretically possible that they could all be struck down with some terrible virus or caught in a freak natural disaster. But really, the chances are vanishingly small.

Andrew’s supporters will therefore argue that removing him from the succession is a gratuitous and pointless sanction. But it’s not really about the practicalities of the thing. It’s irrelevant how likely he is or isn’t to be called to serve. It’s about setting a clear intention and tone – and safeguarding the future of the monarchy.

King Charles has no choice but to shut down all avenues of attack from republicans and class warriors who are using – and will continue to use – Andrew as a way of stirring up public opinion against the royals.

Andrew’s behaviour and character tick every cliched box of entitled toff behaviour. He is exactly the sort of arrogant, bumptious brute the King’s enemies want him to be, a useful idiot who confirms everyone’s worst fears about royalty. So, disarm them. Cut Andrew out and they have no ammunition.

Of course, there is another option, arguably an even better one. Andrew could always remove himself from the line of succession. This would still require an Act of Parliament, but it would spare his poor brother (who, let’s not forget, is really not very well) the agony – and would show that he, Andrew, understands the magnitude of his mistakes.

If there is to be any way back for Andrew, it must surely begin with that: accepting responsibility for his poor conduct and showing, for the first time in his life, a little humility.

It’s the very least he can do for the memory of his late Queen and mother, who loved him to the point of indulgence, his family, who he has dragged so ungraciously through the mud – and, lest we forget them amid all the fire and the fury, the victims of his old ‘friend’ Epstein.