The Office for Budget Responsibility is set for an embarrassing U-turn as it prepares to dramatically hike forecasts for UK growth just months after they were suddenly downgraded.

The OBR slashed assumptions in November, reining in expected productivity growth and warning that the deficit would rise in this financial year.

However, strong numbers in the intervening period mean economists expect the watchdog to reverse some of that gloom, a move that would shrink the deficit and deliver a £15bn windfall to the Chancellor.

Growth in the UK’s dominant services industry has surged in the last three months with profits rising at the fastest pace since November 2015, according to a new CBI survey.

Meanwhile, confidence among businesses and professional services is growing with a further pick-up anticipated in the coming three months.