Like a jack-in-the-box on steroids, he refuses to lie down. Andrew Mountbatten-Windsor has popped up again – this time declaring war on Thames Valley Police. His challenge to the legality of the search warrants that allowed officers to raid his Sandringham home, and the house he was kicked out of in Windsor, is a bold move, to say the least. It’s also another colossal headache for the King.

We all remember the picture of the former prince slumped in the back of a police car after being arrested on his 66th birthday in February. It made headlines around the world. Were those staring eyes a sign that he was scared? Or embarrassed? Or confused? Well, it now seems that those eyes belonged to a man seething with anger at the way he had been treated. Clearly he is still hopping mad – and he wants everyone to know it.

It’s true, of course, that instead of being arrested, Mountbatten-Windsor could simply have been asked to attend a police station for questioning. The presumption is that Thames Valley Police decided to swoop on the man and his property without warning so that nothing could be hidden away. The search warrants had been granted by an Old Bailey judge.

It has now transpired that the former prince has been brooding on his treatment for months. Earlier this year he apparently asked for a judicial review of whether the search warrants were lawful. Thames Valley Police have confirmed the legal proceedings but offered no further comment.

You have to go back almost 400 years to find a member of the Royal Family challenging the lawfulness of criminal proceedings. That was Charles I – and you might remember that it did not end well for him. While Mountbatten-Windsor is certainly not facing the scaffold, the allegations against him of misconduct in public office are serious enough.

So what does he hope to gain by trying to prove that the police got it wrong? The last time he tried to defend himself ended disastrously with his now notorious interview. In the court of public opinion, he has damned himself by pursuing a lengthy friendship with convicted paedophile Jeffrey Epstein. Emails released as part of the Epstein inquiry appear to show that the then prince lied to about cutting off all contact with the financier. There is also correspondence suggesting that during his time as UK trade envoy, he may have passed confidential information to Epstein.

Mountbatten-Windsor has consistently denied all wrongdoing.

But his reputation is in tatters and he now lives a life of virtual exile on his brother’s Sandringham estate. If he managed to establish that the search warrants were not lawful, the facts would remain the same and the police investigation – tricky as it is – would surely continue.

A victory would no doubt give him some satisfaction, but at what cost? The renewed publicity about Mountbatten-Windsor and Epstein is the very last thing the King needs at the end of yet another difficult year. The Palace has withstood the tsunami of headlines spawned by Earl Spencer’s book. It is still negotiating a difficult path with Harry and Meghan, and, in a month, the King will have to walk another tightrope when he attends the Heads of Commonwealth meeting in Antigua. There he will have to face the thorny issue of demands for reparations for Britain’s part in the slave trade.

Oh, how he must wish that his toxic and troublesome brother would just stay in his box and get on with a quiet life.