The real issue had come in 2007, with all new fangled benefits galore to hand out, social spending in the Financial Crisis combined with a horrific loss of tax income saw Government spending saw to 50% of GDP. An the deficit and national debt soared with no money to pay for the 'automatic stabilisers.'
So to 2016, the Tory Government has seen a return to GDP growth and cut Government spending back down to 43% of GDP. The real damage though is in the tax base. There has been no recovery of the fake boom Banking tax take. Nor are there any signs it is coming back.
In April 2016 corporate tax receipts are lower than a year ago despite a growing economy. The tax won't come back. And because of that the deficit remains very high by historical standards at 4.4% of GDP.
With little appetite for tax cuts the roof is not fixed, the next recession is pretty close being at most 3 years away and possibly sooner with Brexit, there is no chance of the deficit being fixed in time. The sun has been shining but he damage was too great is what Osborne will argue.
But this alone makes me wonder about a Corbyn Government. By 2019 plenty of people will have forgotten the 2007 mess and who was at fault or not. When the Tories look vulnerable on the economy they generally lose the election. I wonder if it will come to pass.