They never give up, those Remainers. Like the Japanese soldier found on a Pacific island still fighting the second world war – in 1974, every other day there is another loose shot from the undergrowth. After last week’s Ditchley Park gathering involving Lord Mandelson, David Lammy and others, comes an interview in the Overshoot with Monetary Policy Committee (MPC) member Jonathan Haskel. In it, Haskel makes the claim that Brexit is costing each British household £1,000 a year through lost trade and investment.

The beauty of modelling is that you can get it to tell you pretty much anything you want it to

Let’s start with the assertion that this is a loss per household. In any other context, of course, many of the same people who are promoting the £1,000 per household figure today would argue that the trickle-down effect is a mirage: that wealth stays in the hands of a lucky few. Yet, when it comes to attacking Brexit, it seems that the trickle-down effect is alive and well: if the whole economy suffers a loss of £29 billion then that can be divided up between Britain’s 27 million households and presented as money which is taken out of the pockets of each and every one of us. This is nonsense – if the economy shrinks, it will impact most people, but not in such a direct way.

But let’s pass over that and have a look at how Haskel has arrived at his figure. Needless to say, this is a piece of modelling which tries to predict what would have happened had Britain not voted to leave the EU and compares that with what has actually happened. Given the Bank of England’s pretty appalling record at predicting economic growth, or inflation – which two years ago it was still predicting would peak at two percent – one might well ask the point of this exercise, but never mind.

What Haskel has done is to look at the rate of business investment growth over two periods – 1997 to 2007 and 2010 to 2015 – and extrapolate from those periods to where he thinks investment might be now had it continued at those trend rates. Both lines lead to a similar sort of place, far above the current level of investment.

Eagle-eyed readers might just spot an omission here: what about the period 2007-10? Why doesn’t that feature in Haskel’s reckoning? Those three years were, you might just remember, the years of the financial crash. Haskel has taken a couple of trend lines from the boom years, ignored the recession in between, and used that to calculate where he thinks investment would be now. Then he has blamed the lot on Brexit and ignored the pandemic and the sharpest recession in modern times which followed it, as well as the current global economic difficulties.

It is true that the graph seems to show investment flattened after 2016, but then it had grown sharply from a deep pit in the 2008-09 slump, so you might not have expected it to continue on trend. Moreover, Britain is not the only European country to see a tailing-off in investment – Germany saw a similar tailing-off, beginning a couple of years later. The MPC has already attempted a similar exercise with post-Brexit trade – asserting that the level of goods trade is around 10-15 per cent below where it thinks it would otherwise be. That led to the assertion that a Brexit-related loss of trade has cost the economy 3.2 per cent.

The beauty of modelling is that you can get it to tell you pretty much anything you want it to, if the parameters are right. But no, we would not all have an extra £1,000 to spend had we not voted for Brexit.