Sludge
The Tories inherited a deficit of 157bn - more than 10% of gdp. Unless they cut the deficit to nil by slashing public services, the debt was always going to rise.
It is true that they failed to reduce the deficit over their first parliament - something like the economy is far to difficult to forecast. However now that the deficit is nearer 2% of GDP and debt being around 80% of GDP, the aim now has to be to bring the debt down with less focus on the deficit.