Consumer prices may not be deflating as quickly as Labour’s electoral chances did earlier this month, but — even after £300 billion of quantitative easing — price deflation for the first time in more than half a century is finally here. The Bank of England continues to throw everything at keeping prices rising at close to their 2 percent target. Yet it’s not working. And this is not just about cheaper oil. Core inflation has also been dropping like a rock.

I argued that “deflation was looming” for Britain last year, and feel a little vindicated that it has come to pass. But I don’t feel at all gratified about the thing itself.

In a highly indebted economy such as Britain’s — where private debt dwarfs government debt — deflation is a dangerous thing. Past debts — and the interest rates paid on those debts — are nominally rigid. Unless specifically stipulated as being inflation-adjusted (like TIPS) they don’t scale to price changes in the broader economy.

Under positive rates of inflation, inflation assists in keeping debt under control, by shrinking the present amount of goods and services and labour that equate to a nominal amount of currency. Under deflation, the opposite process occurs, and the nominal value of currency — as well as that of historical debt — rises, making the debt harder to service and pay down, especially with the ongoing accumulation of interest.

On the face of it, that is good news for net savers and bad news for net debtors. But raising the difficulty of deleveraging and debt service can often be bad for both, because debtors who cannot pay default, bankrupting themselves and injuring their creditors. It can also depress the economy, as individuals and firms are forced to stop spending and investing and start devoting more and more of their income to the rising real cost of deleveraging.

With growth last quarter dropping to 0.3 percent from 0.6 percent, this process might very well already be under way. This raises the prospect of the nightmarish debt-deflationary spiral above.

The last thing that the economy needs under that circumstance is more money being sucked out of it through slashing public spending. Sucking money out of the economy will make deleveraging even more difficult for debtors, and slow growth further as individuals and firms adjust their spending plans to lower levels of national and individual income. Yet that is the manifesto that the country elected to power in the election earlier this month. And although Osborne and Cameron can get out of it — via offsetting cuts in spending with tax cuts — if they go through with their election promises, the prospect of recession, continued deflation and rising levels of unemployment loom clearly.

What the economy really needed in 2010 was a deep and long commitment to public stimulus to provide the economic growth needed to let the private sector deleverage. Unlike the public sector, which is a sovereign creditor borrowing in its own currency — the private sector is far from a secure debtor. Private borrowers can — unlike the central government — “become the next Greece” and run out of money.

With interest rates in the last parliament having sunk down to new historic lows, such a thing was affordable and achievable. Instead, by trying to do public deleveraging at the same time as the private sector was deleveraging Osborne, Cameron and Clegg chose a much rockier path, one in which private deleveraging and public deleveraging are slow and grinding. With private debt levels still very high, the country remains vulnerable to another deleveraging-driven recession.