Thinktank says Wednesday’s spending review will amount to boost of £9bn, with £4.5bn already accounted for

The Treasury will need to find an extra £5bn from next year to fund the government’s spending promises, according to the Institute for Fiscal Studies (IFS), which said the increase could undermine the Treasury’s commitment to reduce borrowing.

Boris Johnson said on Monday that Wednesday’s Whitehall spending review, which will set out department funding for 2020/21, would be the “most ambitious spending round for more than a decade”.