The night Prince Philip told me he was a ‘European mongrel’, and happy that way

It was a Monday evening in early 2004 when a group of Europhiles and Europhobes gathered for a Buckingham Palace dinner at the Duke of Edinburgh’s invitation. We were there to discuss the proposed treaty for a European constitution, just written and whose ratification across Europe was about to begin. I had been one of 12 European “thinkers” who had made joint recommendations on what European values should be in its preamble, hence my presence. What followed was one of the most surreal evenings of my life, brought to mind by the three German princes the Duke of Edinburgh insisted should attend yesterday’s funeral.

Evidently he cared about the issue, hosting the dinner after an Atlantic night flight and two public engagements earlier that day. Conversation over pre-dinner drinks was wary – Labour MP Austin Mitchell relieved our awkwardness by switching the lights on his union jack bow tie on and off – and eventually we were ushered through long corridors to a banqueting room, lit by low chandeliers and guttering candles.

The duke wanted to know what threat the treaty posed for Britain and our constitutional arrangements, including, though it was left unsaid, what it meant for the monarchy. Battle was joined, with the well-briefed duke acting as umpire. Soon, William Rees-Mogg was in full spate. His daughter, Annunziata, he said triumphantly, had read the treaty in full and he proceeded to cite various articles, clauses and subclauses that, together, would mean the end of the British constitution as we knew it. Three of the Europhobe contingent then joined him, banging the table and shouting “No to Europe” with such force that the red-jacketed butlers stood back from serving – even the duke looked nonplussed. This was not the usual accompaniment to the royal game and bread sauce.

“Annunziata may have read it,” said the duke in a genial regal put-down, “but John actually wrote it”, turning to Sir John Kerr next to him, who had been secretary-general of the European convention that had drafted the treaty. “Does this mean that the British army will be under the command of the president of the European commission?” Kerr was coruscating. We had listened to fantastical nonsense; no such interpretation was possible nor anything else that had been said, although that was not to stop the Sandringham gamekeeper pronouncing that the common agricultural policy threatened the rearing of the dead game we were enjoying.

Finally came my turn, the duke angling his body towards me. He thought I took a different view to Rees-Mogg and the rest. (It was now obvious that, apart from Kerr, I was the only other pro-European there.) Yes, I said – just as British foreign secretaries had played their role in the 19th-century Congress of Vienna, Europe’s affairs in the 21st century were now to be settled in an emergent Congress of Brussels, but this crucially was a congress of nation states.

Britain had to be part of it. And culturally, I went on, there were six other constitutional monarchies in the European Union. Suggestions that the treaty would seal their abolition were crazed. I profoundly disagreed that British values were more American than European. Then, throwing caution to the wind, I said he, in his person, embodied European-ness and we had to recognise who we British really were.

There was a pause, then the man who wanted those three German princes at his funeral let slip: “Yes, I’m a European mongrel.” The Europhobic atmosphere was marginally pricked. Nobody argued for leaving the EU – it was obvious economically we had to stay. The argument was to what degree the EU was becoming a quasi-state and how much Britain should stand aside.

I know Brexiters want to claim the royal family as unspoken allies – and certainly the casting of the dinner was hardly impartial – but the duke was inscrutable. He may have had fears about the treaty but, by instinct and birth, he was no anti-European or English nationalist. Getting along in Europe, as in the United Kingdom, meant putting spent nationalisms aside and trying to hang together. As long as deep-rooted national institutions, such as the monarchy, were safe, you did what was necessary to keep the show on the road. Just as you accept the untidy settlement that holds Britain together, so accept the same in Europe. He was, after all, the Duke of Edinburgh as well as a European mongrel.

That dinner foretold the Tory passions that would lead to where we are now. Tony Blair was to concede, later in April, a referendum on the constitutional treaty, which in the event never happened because the French in their referendum said non. The agreement morphed into the Lisbon treaty but the seeds of disaster had been sown. If there could be a referendum on the constitutional treaty, why not on a renegotiated relationship with the EU?

The morning after the Brexit referendum, I’m reliably told, one Windsor – Prince Charles – broke cover, privately declaring it a “catastrophe”. The EU had become the best vehicle for promoting sustainability on the planet, he felt, and now Britain was out we would undoubtedly regress. The Windsors are no radicals – they understand that they uphold a system of class and privilege and enjoy the trappings. But they also understand, as Tories did before they made their deadly bargain with English nationalism, that you keep the British show on the road by promoting one-nation values of duty, social inclusion and essential decencies, one of which is rubbing along with European neighbours, making common cause where it matters, such as on climate.

Looking back, what Prince Philip was doing at that dinner was assuring himself that the royal family would not fall victim to an excess of federalist zeal. I think he ended up assured. The current Conservative party could do with some of the royal family’s brand of conservatism, that has served it so well over time. Instead, it has Boris Johnson, with the slow car crash of Brexit the result. Philip was right – we British are mongrels and we belong in Europe.

• Will Hutton is an Observer columnist