The path of spending cuts over the next five years ‘seems more uncertain than ever' following Wednesday's Budget announcement, a top public finance economist has claimed.

In his post-Budget analysis, Paul Johnson, director of the authoritative Institute for Fiscal Studies (IFS) think-tank, said the change in direction signalled by chancellor George Osborne's plan to inject £20bn extra cash into public services at the end of the decade raised serious expenditure questions.

Mr Johnson said predictions of lower inflation, debt payments and welfare bills from independent forecasters the Office for Budget Responsibility (OBR) showed a slight strengthening of the public finances in over the next five years.