I think you'll find we were talking about a cliff edge on a graph,
which does not affect very many. That was my point about exaggeration.
In any case, the predicted 'cliff edge' is more of a tick shape. The GDP will dip a little, may not even long enough to qualify as a technical recession.
The red plot is the worst case scenario according to the IMF. You can see that the economy will recover strongly after the dip at the end of 2017.
The more likely scenario is the blue like, a friendlier version to brexit. Evenso, the difference is +/- 2%
EDIT: thanks to oldtom pointing out that the graph does not show where the real economy is.
The real economy is about 3% above the blue plot, since depreciation pushed up GDP.