Dragging the Queen into politics leaves a sour taste

David Cameron's indiscretion and the current Brexit mess are a reminder that constitutional vagueness is no longer acceptable

Queen Elizabeth II with Britain's then prime minister David Cameron in 2012. AP

"The first rule of Fight Club is: you do not talk about Fight Club. The second rule of Fight Club is: you do not talk about Fight Club." The famous quote comes from Chuck Palahniuk's novel of the same name, which became a cult film starring Brad Pitt and Edward Norton two decades ago. It could equally be applied to discussions with Queen Elizabeth II. In the unwritten rules of British public life, the first rule of those private chats is: you do not talk about discussions with the Queen. Like the constitution, it might not have been transcribed onto paper – but it might as well have been carved in stone. Breaking it is considered a cardinal sin.

For decades and down through generations, the weekly conversations between the sovereign and the British prime minister have been treated as utterly confidential. Writers and journalists have imagined vividly what goes on behind closed doors – perhaps some political gossip over a pot of Earl Grey, and advice and confidences flowing freely on both sides – but the talks have remained just that: private.

On the death of Diana, Princess of Wales, there was much speculation about the turmoil and self-examination it created within the royal family. Then prime minister Tony Blair was reported to have had frank conversations with the Queen about how to handle the profound wave of public sympathy and the ensuing public chastisement of the royal family. But Mr Blair has never openly discussed what took place during those meetings. Others who worked in the royal household at the time have told me in general terms that Mr Blair’s advice was respectful, thoughtful and useful.

Certainly the British royals seemed to rethink their strategy in dealing with their public perception afterwards. They changed some advisers and altered the way they reacted to criticism in newspapers – without having their privacy breached. But now two Conservative prime ministers, Boris Johnson and David Cameron, have broken the first rule of royal club. Mr Johnson blurted out that in his first conversation with the Queen, she wondered why anyone would want the job of prime minister. It was self-serving on Mr Johnson's part, reminding voters what a difficult burden he was prepared to shoulder. But expectations about Mr Johnson are generally so low that Blundering Boris is what many have come to expect. The criticism was duly muted.

Not so with Mr Cameron, who published his memoirs this month. As prime minister, Mr Cameron plunged Britain into the 2016 Brexit referendum, at a time when leaving the European Union was of little or no concern to the majority of British voters, although it was troubling some elements of his own party. Unfortunately, Mr Cameron's "solution" – which he foolishly hoped would appease Tory Eurosceptics and make the whole matter go away – was a disaster for him, his party and the country. Moreover, his policy of austerity has been condemned as a political decision that lacked real economic vision.

In these very unstable times the monarchy is a rock within the British consciousness

We can debate these issues, but there is one general point about Mr Cameron that most people who meet him tend to agree upon. He is, in the words of a former Conservative MP and The Times' columnist Matthew Parris, "a good man" and "a pleasant person", even if he has made serious political errors. As a journalist, I met Mr Cameron on a few occasions, sometimes in the company of my children, and he is someone who is warm and easygoing. I liked him personally and so did my children. Like Mr Johnson, he is an old Etonian, but unlike the current prime minister, Mr Cameron appreciated the value of hard work. Yet now the ex-prime minister has done something that has surprised me and annoyed or disappointed many. In his newly published memoirs, he says of his weekly audiences with the Queen: "I was a much better prime minister than I would have been without those weekly doses of wisdom." So far, fair enough. But then he went so far as to say publicly that he once asked the Queen to "raise an eyebrow" to indicate her opinion on the 2014 referendum in Scotland for independence. Alarm bells begin to ring.

During that highly contentious campaign, which I spent in Scotland, the Queen did say that Scots should think very carefully about how they voted. It was hardly a clear entrance into politics. But following Mr Cameron's indiscretion about "raising an eyebrow",  Buckingham Palace has been unusually quick to express displeasure about his breach of confidentiality and protocol. It also comes as the Supreme Court is expected to announce its verdict tomorrow on whether Mr Johnson effectively lied to the Queen about the reasons for "proroguing", or suspending, parliament.

All this leaves a sour taste. At the age of 93, the Queen has served the UK exceptionally for more than 60 years, making her the world's longest-serving current monarch. The monarchy remains very popular. These two facts are related. In these very unstable times the monarchy is a rock within the British consciousness. Dragging the Queen directly into politics – even unintentionally – is unfortunate and wrong.

Then there is Britain's famously unwritten constitution. The current Brexit mess demonstrates that this constitutional, legal and political vagueness is no longer tolerable. Relying on precedent and past common sense or good deeds is not enough. We need a written constitution or a clear indication about the relative powers and responsibilities of the monarch, the courts, parliament and the government or executive. It will not be easy – but it is necessary. To quote Fight Club once more: "When the fight was over, nothing was solved, but nothing mattered. We all felt saved." Perhaps it is not possible to solve everything with a perfect constitution, but to save the unity of this increasingly disunited United Kingdom, we need to restore trust with a clear outline of which institutions are responsible for what – and why.

Gavin Esler is a journalist, author and presenter