Both the Conservatives and Labour are engaged in a “conspiracy of silence” about what will happen to the public finances after the election, the head of a leading economic think tank has said.

       Responding to the spring Budget, Paul Johnson, director of the Institute for Fiscal Studies, said both parties were not being straight about the “scale” of the trade-offs they will face after voters go to the polls.

       “They, and we, could be in for a rude awakening when those choices become unavoidable,” he told a press conference on Thursday.

       Mr Johnson also warned that the UK was facing its most difficult period financially since the Second World War.

       “The combination of high debt interest payments and low forecast nominal growth means that the next parliament could well prove to be the most difficult of any in 80 years for a chancellor wanting to bring debt down,” he said.