Leaving the EU has reduced Britain’s GDP by up to 8pc, according to a devastating US study

The latest such assessment comes in the form of a paper from the US-based National Bureau of Economic Research (NBER). This concludes that Brexit has reduced UK GDP by 6pc to 8pc, far more than most previous estimates.

Investment is worse off by between 12pc and 18pc, employment by between 3pc and 4pc, and productivity also by between 3pc and 4pc. There have been few more devastating assessments than this.