[explanibrag]

What if England doesn't realise it could be better at heavy industry than it is at financial services?

Edit: shouldn't your point be "no matter what England does, someone will always benefit from free trade"? What's globally optimal isn't necessarily optimal for England.

[jimmytidey]

If England was smarter than it is, then it would be richer than it is. Perhaps if they had the smarts to notice they were better off doing heavy industry they would be better off. But, England ought to be trying its very best because individuals are motivated to have as much nice stuff as they can.

Free trade does ensure global optimality. It also ensures a better outcome for every country that participates. It does not ensure that every single person within every country will have got richer. It does ensure that, on average, every citizen of every country will be richer.

Again, only within the comparative advantage model we are discussing.