Wholesale record prices are highly visible—a few prices in company catalogues account for the bulk of sales—which suggests that firms could plausibly co-ordinate on an agreed tariff.

The WTO’s rules allow them plenty of scope: after two decades of unilateral tariff-cutting most of their tariffs are well below their “bound” rates, the ceilings agreed in the trade club.

The nine countries also have agreed to develop a single tariff schedule as well as common rules of origin that will make it easier for businesses to take advantage of the agreement.