The Treasury’s predictions during the lead-up to the EU referendum were wrong to the tune of £100 billion, according to a new report.

It calls the Project Fear campaign, spearheaded by the former chancellor George Osborne, as a “giant error” and a “gross miscarriage of government”.

Mr Osborne’s “scary rhetoric about a return of the Great Recession now looks preposterous,” said the study’s author, Timothy Congdon, a leading economist.

The difference between the Project Fear forecast and the reality was 4.6 per cent of GDP, according to the report, which will be published in the May edition of Standpoint magazine.