In the aftermath of last December's belated – to the point of wintry – Autumn Statement, Paul Johnson, director of the Institute for Fiscal Studies (IFS), repeatedly said it would be 'inconceivable' for unprotected Whitehall departments to manage real-terms cash cuts averaging upwards of 30%.

For Mr Johnson, it would also be ‘inconceivable' for local government to follow the same spending review trajectory and face effective 40% cutbacks by 2018. Surely ministers in the next fixed-term parliament would have to lower welfare entitlements or raise taxes?