Instead we had lots of decisions being made by lots of businesses to defer future investment plans in the UK till things got clarified followed by contingency plans to invest within the EU27 instead in order to safeguard market access.  It takes a couple of years for all those micro decisions to have a discernable macro effect in the real economy, and even longer for them to be reflected in national statistics.

So we are, even now, only seeing the very beginnings of the Brexit effect on the UK economy, and the first effect is, as you say, a loss of the forward momentum the UK economy had at the time of the referendum. That will be followed by a further slowdown and perhaps even outright recession just as the A50 talks are nearing their denouement. Not the best context for a successful negotiation.

However the converse is also true. Once the negative recessionary momentum builds up it will become increasingly difficult to stem the flow of bad news - even after some real recovery has taken place in some sectors.  But we have to be looking at this in terms of the next 5-10 years, and decades thereafter, not the next 3 months, and after that period a lot of irreversible damage will have been done to a lot of real people's lives.

Index of Frank's Diaries