Please keep shoving the royal oar in, Your Highness

Charles's interventions may be predictable, but what politician of any party would criticise vested interests such as the big supermarkets? Happy birthday, HRH

Older, bolder: The Duke and Duchess of Cornwall in Jew Town, Kochi, south-west India on Thursday, his 65th birthday (PA)

Wherever one looked last week in media-land, on magazine covers and television screens, in the op-ed columns of national newspapers, on blogs and in the Twittersphere, Prince Charles was omnipresent. He could be seen on the lunchtime news graciously perambulating a red carpet at Colombo airport, in his capacity as the Queen's representative at the Commonwealth conference.

Just as one newspaper ceased to congratulate him on the achievement of his 65th birthday, so another presumed to lecture him on the responsibilities that attended his new-found, pensionable age. And together with these celebrations, these patriotic effusions and the footage of HRH greeting his Sri Lankan entourage came a faint hint that one of the things he might profitably do as a senior citizen was henceforth to keep his mouth shut.

The Prince's interventions in our national life come round as regularly as the Victorian muffin-man, and with quite as much incidental clamour. Even as a child, back in the 1970s, when the country was aflame with industrial unrest and union militancy, I seem to remember him favouring us with some remarks about the fortitude of the "ordinary British bloke". Since then there have been assaults on the "monstrous carbuncles" of contemporary architecture and planning developments that threaten what is left of our green and pleasant land, together with observations on renewable energy sources, organic farming and every good, brave, eco-friendly cause worth the name. As for the Prince using the current, guest-edited number of Country Life to weigh in with a defence of the farming community in its fight against the supermarket chains, this was about as foreseeable as the rapt applause that greeted Sachin Tendulkar as he strode to the crease in Mumbai on Thursday morning.

Public reaction to the sight of the Prince in full flow on one of his pet projects takes a variety of forms. There are those who believe that, as the heir to the throne, he is entitled to speak his mind on any subject that appears in the file of press cuttings carried each morning to the royal study. There are others – a small minority, but disproportionately vocal – so infuriated by the mere existence of a Royal Family in this supposedly democratic age that for any one of them to say anything about anything is regarded as a piece of desperate effrontery. But lurking behind both these constituencies is a substantial body of opinion with a habit of suggesting comments about farming, supermarkets and so on are in some sense "political", or at least controversial, and should therefore not be entertained by someone who is, at any rate theoretically, supposed to profess a scrupulous impartiality.

Undoubtedly, the expression of strong opinions can sometimes bring a monarch, or even a monarch-in-waiting, into grave difficulties. But one doesn't have to be a paid-up haunter of the pavement outside Buckingham Palace to think that Prince Charles – short of registering support for a particular political party – should be encouraged to say what he likes about life in modern Britain whenever he wants to say it, if only because the expression of a genuinely controversial opinion is something that the modern politician would usually run a mile to avoid. It is all very well our political leaders queuing up to disparage such soft targets as the utility companies, but would Ed Miliband care to criticise, let us say, the leading supermarket chains, or the fast-food industry, or the proprietors of The Daily Telegraph, to name only three entities that could do with some intent public scrutiny? No he would not, because by and large the mechanics of modern-day political life consist of trying not to give offence.

The engrained reluctance of modern politicians to strike out on a line of their own was brought home to me some years ago when, at the invitation of one of the football magazines, I attended a Norwich City home game in the company of my local MP, Charles Clarke. Mr Clarke, who may then have been Home Secretary, brought an aide with him and also a tape-recorder, which I thought faintly superfluous. It happened to be the week in which Roman Abramovich had announced his intention of buying Chelsea FC. What, I wondered, did one of the most senior politicians in the country – a football fan, no less – think of this? Clarke looked worried. "Is this off the record?" he wondered. I assured him that it was. "Well then, it stinks."

I thought then, and continue to think, that it was a bit wet of a Labour Home Secretary to conceal his real opinion of a business deal with serious implications for British sport merely because his prime minister was happy to let a Russian oligarch of uncertain provenance muscle in on the territory, but no doubt Mr Clarke had his reasons.

The consequence of this timidity, and the desperate desire to appease the middle-class voters on whom electoral success is always thought to depend, is that the really serious issues affecting our lives go more or less unventilated. Who is there, for example, other than the Archbishop of Canterbury who is prepared to take on some of the implications of 21st-century consumer materialism, as he did in the recent suggestion that we would all be better off – financially and morally – if we spent just a little less on Christmas presents. Like Prince Charles, Justin Welby is routinely reviled by non-believers for being a "meddlesome priest" and interfering in things that don't concern him when his real interest should lie with his half-witted and diminishing flock. On the other hand no politician would dare to question the widely held assumption that the first duty of all patriotic citizens is to spend as much money as they can on high-end retail goods, for consumer spending means growth and growth means happiness, and bless us all, we can't have the nation's children denied their Christmas.

There may still be an abstract called "public discussion" these days, but by and large it is not conducted by politicians, who have party lines to toe and interest groups to conciliate – all the dead weight of oligarchy that continues to weigh us down and will eventually drown us. This is why it is so vitally important that the voices of the Prince of Wales and the Archbishop of Canterbury should be heard as often as possible. They may very well be only the last surviving symbols of a temporal-cum-spiritual system that perished with Queen Victoria. On the other hand, they are serious people with the advantages of a message and an audience – both qualities which the modern politician, for some mysterious reason, seems to lack.