These two may have welcomed a second Asian intervention: the unusual publication by Japan’s foreign ministry of a Brexit paper. Japanese companies, it said, were huge employers in Britain, which took almost half of Japan’s investment in the EU last year. Most of that came because Britain is a gateway to Europe. The paper advised Mrs May to try to retain full access to the single market, to avoid customs controls on exports, to preserve the “passport” that allows banks based in London to trade across Europe and to let employers freely hire EU nationals.