Analysis: Figures were being bandied about like confetti yesterday as Gordon Brown sought to justify his Keynesian policy of �borrow and spend� in an economic downturn while David Cameron upbraided the UK Government for its financial profligacy.

Figures were being bandied about like confetti yesterday as Gordon Brown sought to justify his Keynesian policy of "borrow and spend" in an economic downturn while David Cameron upbraided the UK Government for its financial profligacy.

In an at times stormy Commons session, the Prime Minister puffed out his chest and declared that given the UK's public sector net debt was only 37.6% of GDP, then it was the right time, in a downturn, to borrow to help sustain the economy.

He quoted 2008 figures from the International Monetary Fund, aimed at showing how it was not all that bad in Britain - America's net debt was 46.3% of GDP, France's was 55.5%, Germany's 56.1%, Japan's 94.3% and Italy's 101.3%. "The reason we can borrow at this time - which is the right policy is that our levels of national debt are low," insisted Mr Brown, banging the dispatch box. His debt forecast for this year had been £43bn.

However, noting how some predicted a record budget deficit as high as £64bn, the Tory leader asked: "Isn't the £64bn question this: why, when business and families need more help, have you left the cupboard so bare?"

Of course, net debt is only 37.6% if the debt of Northern Rock is kept off the books. If, it is kept on, then the figure goes up to 43.4% or a cumulatively whopping total of £645.3bn. This means that Mr Brown's fiscal rule - the sustainable investment rule - which says national debt must be below 40% of national income, is to all intents and purposes blown away. However, the Treasury insists the fiscal rules allow for "temporary and exceptional events" ie Northern Rock, which means, it argues, they do not have to go on the balance sheet.

Then, of course, there is the little matter of the £37bn bailout for HBOS and RBS, which takes the level of debt even higher. Yet despite all the financial massaging, analysts predict that Britain's borrowing could hit a mighty £64bn this year, £100bn the next and as much as £120bn by 2010 - the year of the next General Election. Debt to national income, therefore, is likely to break through the 50% barrier in the coming months.

Added to that, the lower levels of income - corporation tax was down 8% in September - will mean that Mr Brown's other fiscal rule, the "golden rule" of only borrowing to invest and balancing the books over the economic cycle, also looks like a dead duck.

Internationally, the mood is not much better. The UN last night suggested the global downturn would raise world unemployment to 210m people by the end of next year, its highest rate for a decade.

Ben Bernanke, chairman of the US Federal Reserve, noted how his country's economy was not likely to emerge from its dark tunnel for a while, saying it was "likely to be weak for several quarters and with some risk of a protracted slowdown".

From Italy to South Korea and the United Arab Emirates to Australia, governments have been bailing out their banks to ease the effects of the credit crunch.

Elsewhere, growth forecasts are being cut but to levels Britain, Europe and America could only dream of.

Egypt, for example, said its growth rate could slow to just 6%, while China's slackened to a mere 9%.

Yesterday, as he addressed MPs, the PM's main line of defence seemed to be to offer comfort that our neighbours had borrowed much more than we had, so it was alright to let rip with the national credit card.

Moreover, government programmes would be brought forward to keep investment being pumped into the economy but this might not prove easy as such schemes take time to implement.

In the end, the buck might stop with Mr Brown but the bill will end up with the taxpayer.