how much will we lose?

When May invokes Article 50 and forces the UK out of the EU she will begin an economic disaster. The extent of that disaster is not clear. At best it could be a recession that reduces GDP by 3% at worst it could be a depression that shrinks GDP by 10% or more. Anything beyond a 10% reduction in the economy is too awful to even contemplate but Jack Womack’s Random Acts of Senseless Violence is going to be a good guide to the horrors of that.

At minus 3% things will not be too much worse than they are already. The welfare state will cease to exist but the NHS and many of the UK’s key institutions (universities and museums and so forth) would probably survive. At minus 10% that would not be the case.