I don’t think I’d make a good casting agent. Somehow the idea of Ricardo Montalban as Gordon Brown doesn’t really convince. As for Hervé Villechaize as David Cameron: let’s not.

I should explain. Montalban and Villechaize played Mr Roarke and Tattoo in the 1970s TV series, Fantasy Island. At the start of each episode, Tattoo – a dwarf – would ring a bell and shout “The plane! The plane!” as the latest guests arrived. Over the course of the next hour, we would then watch the guests play out their fantasies. But nothing came free; they all paid a price. The tension between realising their fantasy and the cost was what gave the programme its thrust.

I doubt that the young Gordon Brown thought that watching Fantasy Island would be a worthwhile preparation for political leadership. Mr Cameron? That’s anyone’s guess. But they both should have done, because it’s not merely that the series title is remarkably apposite. So, too, is the fundamental message of the series: fantasies are all very well, but they have to be paid for.

Both the Prime Minister and the Leader of the Opposition are conducting Fantasy Island politics. Both promise “world-class” public services. Mr Brown says his prescription is the only way, and the Conservatives will make cuts. Mr Cameron says . . . oh, who cares? It doesn’t matter. Both men are having a Fantasy Island argument for a Fantasy Island electorate through the Fantasy Island media.

Neither of them are even acknowledging, let alone confronting, the biggest issue of all in the funding of public services: where’s the money going to come from? That question is not about tax cuts. It’s not about stealth taxes. It’s not about any of the ultimately irrelevant issues about which politicians scream.

It is about demography. It is about that, as a country – as a continent, indeed – we are getting older. And that means tax funding won’t be enough.

The median age in most EU member states is now over 30. By 2020, 20 per cent of the EU population will be over 60, compared with 15 per cent in 2005. More than 5 per cent will be over 80.

Individually, that is wonderful news. Fewer children means higher disposable personal incomes. And longer life expectancy is – for most of us – a good thing in itself. But taken collectively, problems arise. Given present “pay as you go” funding arrangements, where taxes are collected and spent on public services, such as healthcare, older people become a financial burden, since they require more medical attention and impose more costs. The greater the number of older people, the greater the burden.

Worse, the more pensioners there are relative to those in work – who pay the taxes which pay for the care needed by older people – so the worse the financial problem is.

According to the Institute for Public Policy Research, the percentage of gross national product spent on long-term care can be expected to rise from 1.8 per cent in 1995 to 5 per cent in 2031. To put this in context, spending on the entire NHS was around 6 per cent when Labour took office. Assuming that the bill for long-term care is to be paid mostly – as at present – by taxpayers, we will need to find more money, from a shrinking taxable population, to pay for extra services that cost almost as much as the NHS only a few years ago. I’d call that Fantasy Island economics.

To be fair to Mr Brown and Mr Cameron, they are merely the latest political leaders to ignore reality. None of their predecessors, save Margaret Thatcher, have been any more grounded in Reality Island – and the beneficial impact of Mrs Thatcher’s pension reforms was destroyed by Mr Brown as Chancellor.

Both the supposedly serious parties, as well as the Lib Dems, have ruled out anything other than tax funding for healthcare, to take the most expensive example. But the sums don’t add up. We cannot go on funding healthcare – or education, or welfare, or pretty much anything else you care to think of – as we do now. Because there just won’t be enough of us working to pay.

Aha, says the Government (to the extent that it says anything about this): Raise the Retirement Age! And yes, carrying on working until 68 (as the Government plans) will help. A bit. But the growing prevalence of obesity, heart disease, cancer and other chronic conditions will undermine much of the impact on tax revenue of a later retirement age.

What makes the sterility of the argument over public services all the more ridiculous is that none of this need be a problem. If, instead of using taxes to fund services on a “pay as you go” basis, we (to use the jargon) used funded financing, where money is invested throughout people’s working life, the demographic equation would be irrelevant.

By saving a fraction of our earnings each year, the weight of those repeated contributions to the principal, plus the interest earned on them, would accumulate by retirement to a capital sum sufficient to buy an annuity, or even a perpetual income, that would cover the pension and other costs of old age – including ill-health and chronic conditions such as heart disease and cancer.

Instead of society and each individual facing a financial crisis as we age, we would each save for our own protection, with the State stepping in to help those who have nothing to save.

But on Fantasy Island, no one has any wish to speak about reality. Instead, our very own Mr Roarke and Tattoo blather on about how wonderful life will be if we let them get on with it. And we let them.

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