We need to put this austerity in context. In order to post a surplus in 2020, we will be borrowing more in the intervening years, as the surplus only exists in that year due to deferred corporation tax receipts. We will be back to deficit in 2021 presumably but the OBR was not asked to look at that so that is 'responsible'. This is all happening due to election promise 3 of 3 not yet broken.
The debt is projected to double under the current chancellor. This is due to the global slowdown. The inherited debt is due to Labour though.
None of this is necessary nor even achieving what it is meant to. The best way to reduce our debt would be to focus on growth and productivity. Am very glad am not disabled and rely on benefit. Should I ever have a capital gain - drinks all round!