I don't really want to scare the beejabbers out of you but I have a feeling that those saying we can just keep on borrowing are whistling as they shamble past the graveyard. For we've got not just huge and ongoing deficits, a slump in growth and a spiralling national debt. We've also got demographic changes happening:

The combined effects of an ageing population and a more unstable economy will lift the cost of borrowing radically in the coming years, Barclays has warned. In its closely-watched Equity Gilt Study, the lender predicted the average long-gilt yield – the government interest rate which effectively influences borrowing costs across the entire economy – would rise from its current level of around 4pc to 10pc or beyond.

Now the problem with that is ably laid out in this book, "This Time is Different" (recommended for those who like facts at fingertips about debts and defaults). For our national debt is expected to hit 100% and go beyond that in the not too far distant future. And if the interest rates we have to pay on that go over 10%....well, as the book explains, looking at the 800 or so incidences of debt default by governments, when interest to be paid passes 12.5 % of GDP that's the general trigger that raises the likelihood of such default from a well, mebbe to "so when will it happen, Tuesday or Friday?"

You can see that a 10% or more interest rate on a 100% or more national debt gets us close to or over that 12.5% danger mark. Which means, essentially, that we've got to get a grip on the budget. I mean, well, we could default, but as a huge chunk of that debt is owed to our own pensions we might not really like that all that much.

The book is also the source of the fabulously interesting fact that Greece has been in default on its national debt for some 50% of its time as an independent nation. But perhaps that's not all that cheering under current circumstances either.