John Bolton says the UK can strike a quick trade deal with the US. This reminds me of an under-appreciated fact - that it is not trade rules that are significantly holding back UK exports.

Brute facts tell us this. As part of the EU, the UK and Germany have the same trading rules. Last year, however, Germany exported $134bn of goods to the US whereas the UK exported only $65.3bn. Per head of population, Germany's exports to the US were therefore 60% higher than the UK's. Much the same is true for other non-EU nations. Last year Germany exported $11.8bn to Australia whilst the UK exported just $5.9bn, a per capita difference of over 50%. German exports to Canada were $12bn whilst the UK's were $7.3bn, a 28% per capita difference. German exports to Japan, at $24.1bn were 2.2 times as great per head as the UK's. And German exports to China, at $109.9bn were three times as great per capita as the UK's $27.7bn.

Now, these numbers refer only to goods where Germany has a comparative advantage over the UK. But they tell us something important. Whatever else is holding back UK exports, it is not trade rules. Germany exports far more than the UK under the same rules.

As for what it is that is holding back exports, there are countless candidates - the same ones that help explain the UK's relative industrial weakness: poor management; a lack of vocational training; lack of finance or entrepreneurship; the diversion of talent from manufacturing to a bloated financial sector; the legacy of an overvalued exchange rate. And so on.

If we were serious about wanting to revive UK exports, we would be discussing what to do about issues such as these. Which poses the question: why, then, does the possibility of trade deals get so much more media attention?

One reason is that the right has for decades made a consistent error - a form of elasticity optimism whereby they over-estimate economic flexibility and dynamism. Back in the 80s, Patrick Minford thought, mostly wrongly, that unemployed coal miners and manufacturers would swiftly find jobs elsewhere as, I dunno, astronauts or lap-dancers. The Britannia Unchained crew think, again wrongly, that deregulation will create lots of jobs. And some Brexiters in 2016 thought sterling's fall would give a big boost to net exports.

In the same spirit, they think free trade deals will raise exports a lot. But they won't - and certainly not enough to offset the increased red tape of post-Brexit trade with the EU. Jobs and exports just aren't as responsive to stimuli as they think. The economy is more sclerotic, more path dependent, than that.

Secondly, the BBC has a bias against emergence. It overstates the extent to which outcomes such as real wages, share prices or government borrowing are the result of deliberate policy actions and understates the extent to which they are the emergent and largely unintended result of countless less obvious choices. In this spirit, it gets too excited about trade deals and neglects the real obstacles to higher exports.

But there's something else. Perhaps the purpose of free trade deals is not to boost exports at all. It is instead largely totemic. Such deals are one of the few things we'll be able to do after Brexit that we couldn't do before. They are therefore a symbol of our new-found sovereignty. They are, alas, largely just that - a symbol.