A new study by Cambridge University Centre For Business Research,
HOW THE ECONOMICS PROFESSION GOT IT WRONG ON BREXIT
Ken Coutts, Graham Gudgin and Jordan Buchanan

"In light of these shortcomings it might have been expected that the profession would take extra care to make its assessment of the potential impact of Brexit as fair and accurate as possible. A further failure would add substantially to the questioning of the underlying soundness of economic theory and practice related to forecasting. We argue in this paper that this did not happen and that much of the economic assessment of the impact of Brexit has been flawed, leading to a conclusion that the profession does indeed need to reassess its methods."

"Our conclusion is that most estimates of the impact of Brexit in the UK, both short-term and long-term, have exaggerated the degree of potential damage to the UK economy. We stress at this point that this is not a politically-driven exercise. Most of the four-person team behind the research for this and our other papers voted ‘Remain’ in the 2016 referendum and would do so again if given the chance. Our purpose is rather to establish a sound basis for the ongoing debate on the likely potential economic impact of Brexit, and more generally to question the quality of economic analysis in dealing with major, macroeconomic policy issue like Brexit. "
http://www.cbr.cam.ac.uk/fileadmin/user_upload/centre-for-business-research/downloads/working-papers/wp493.pdf