In a nutshell, the government borrows £118billion and injects it into the economy now. This, it is hoped, will stimulate economic activity thus boosting tax income meaning that the receipts to the treasury will increase to repay the amount borrowed.
If the government, no matter what 'colour' it is, does nothing the country will descend further into recession thus seeing tax revenue dwindle further and necessitate further borrowing at a later date.
This is a calculated gamble to boost the economy and hopefully preserve jobs in the short term. No doubt, there will be pain further down the road but only when the economy is strong enough to withstand it.
Historically, governments have been too slow to react to recessions and this is a proportionate response to a massive global problem. If this proves successful, we could even see an early move to Stirling thus seeing the value of the pound strengthen.
I never thought I would say it but, it appears that Gordon and his bunch of morons appear to have at least understood the problem and have taken a sensible approach to remedying it.