Gordon Brown’s bad patch just got worse. Even as the prime minister sought to turn the political focus away from questions about his authority and on to his vaunted ability to handle the financial crisis, he has taken a direct hit on his core competence. The blast came from a cross-party committee of MPs, which on Wednesday produced a withering critique of the Budget.

No aspect of the statement delivered by Alistair Darling just a couple of weeks ago escaped unscathed. The committee called Treasury growth forecasts “optimistic”; queried the efficacy of government stimulus initiatives, such as the temporary reduction in the value added tax rate and the stamp duty holiday for house purchases; expressed deep concern about the public finances; and questioned the basis and impact of the planned top rate of 50p income tax.