Protestors are welcome to protest but not disrupt the majority enjoying the Coronation - Bill Carmichael

Republic also claims to be coordinating other, probably smaller, demonstrations across the UK.

My first thought on reading this was: ‘Haven’t they got anything better to do?’

To which the resounding answer is: ‘No, of course they haven’t.’

I suspect the sort of people cluttering up Trafalgar Square tomorrow can normally be found glueing themselves to the roads to stop ambulances taking seriously ill people to hospital in the name of saving the planet.

My second thought was that those placards are simply factually incorrect. If you are a British citizen then Charles is your king whether you like it or not.

But good luck to them. They are entitled to their views and I for one am very glad to live in a country where dissent is not only tolerated but actively facilitated.

When you see those yellow placards being waved - no doubt massively outnumbered by the red, white and blue of union flags - it is a good indication of the health of our democracy.

I would count myself as a reluctant monarchist. In my youth I drew the ire of my tutors when I refused to stand for the National Anthem at the end of a formal dinner at my Cambridge college.

But decades of watching our late Queen Elizabeth, and her utterly selfless devotion to the service of her country, brought me round.

The monarchy is far from a perfect system. For some years now I have taught the British Constitution and Monarchy to university students and I am used to seeing their astonishment, particularly those from overseas, when I explain the details of a frankly crazy system.

Is the monarchy fair? Of course not. Why should anyone get a job simply because of who their parents are?

A hereditary system is clearly inequitable, although I bet few of those protesters in Trafalgar Square will complain when their elderly parents die and leave them a mortgage-free house. Isn’t that unfair too?

The truth is lots of people are prepared to turn a blind eye to the unfairness of the hereditary system when they benefit from it.

And don’t get me started on that undemocratic feudal relic, the House of Lords, packed to the gunwales of course with unelected, unaccountable socialists and republicans, and which, unlike the monarch, can still influence legislation. Is that fair? I think not.

But, in the name of impartiality, I encourage my students to think of the possible advantages of the monarchy too.

Compared to many Western countries, the UK has been remarkably stable for more than 300 years, eschewing the extremes of communism and fascism, and being governed by a series of mainly moderate governments.

Could it be that the monarchy has had a role to play in that? Could a queen or a king be part of the essential glue that holds an increasingly diverse society together?

The genius of the British system is that we have stripped the monarch of all vestiges of dictatorial power - thanks to the Magna Carta in 1215; the Civil Wars of the 1640s and the Glorious Revolution and the Bill of Rights in the 1680s - while retaining the powerful symbolism represented by the Crown.

So I welcome the protests tomorrow. They are free to wave their placards and make their case.

But I draw the line at them stopping other people going about their business or spoiling the enjoyment of others.

So I was glad that the new Public Order Act came into effect this week, which bans “serious disruption” such as glueing themselves to roads or public transport.

As Security Minister, Tom Tugendhat, said “protesters have the liberty that anyone in the United Kingdom has to protest; what they don’t have is the liberty to disrupt others.”

Quite right.

As for me I will be raising a glass to King Charles and Queen Camilla and wishing them well.

Charles has a very tough act to follow, but I wish him every success. And if he can do half as good a job as his late mother, he will make the country proud.