Gordon Brown as Chancellor and Prime Minister spent money profusely, believing that he could spend the British people's money more appropriately than they could spend it themselves, and by a political desire to have a large section of the populace on state largesse and thus supportive of a party that promised big spending. The result was to make the UK hugely indebted, with an annual deficit that required borrowing to sustain that spending and increase the debt year by year.
The coalition government that followed him took action to reduce the deficit by a reduction in government spending. This was the so-called 'austerity' package, although some critics claimed it was more talk than substance, with reductions in the increase in the debt, rather than in the debt itself.
Crucially, though, the policy was not only one of austerity. It was accompanied by quantitative easing (QE), or increasing the money supply to reduce the more baneful effects of austerity. Latterday Keynesians claim that government should have increased its spending to stimulate demand instead of decreasing it to tackle the deficit. Their critics in turn suggest that it is not demand by government that sustains real economic growth, but investment by businesses in anticipation of future private demand.
The United States followed a similar policy of reduced spending combined with QE, whereas the eurozone countries led by a cautious Germany did not. They imposed austerity on the over-extended countries of Southern Europe, but without the QE used in the UK and the US.
Britain and America experienced significant economic growth after a few flat years, whereas the eurozone countries did not. Anti-austerity campaigners have suggested that the recovery is weak, perhaps "not even real," but the evidence does not support this. The empirical result suggests that the combination of austerity and quantitative easing has worked, but that the eurozone policy did not. Significantly, the QE countries did not suffer the big rise in inflation which some critics predicted. In 2015, the eurozone countries announced their own quantitative easing, some 7 years after the UK and US did so.
The conclusion has to be that government was right to use austerity and quantitative easing to deal with the crisis. They did not repeat the mistakes that turned a recession into the Great Depression of the 1930s.