I have no doubt that my hon. Friend is right about the application of WTO rules, but what happens if a free trade agreement is already in place? Would that free trade agreement have to be renegotiated? Suppose we have a free trade agreement with the EU and we want to put a carbon tariff on German steel, which is very carbon intensive. Are we going to be tied in knots by what we might have already agreed? How does he think that would be resolved?