Theresa May, the British prime minister who has the historical misfortune to be guiding her country’s economy through its most difficult time since the dark days of hyperinflation and the International Monetary Fund (IMF) bailout in the 1970s, wants to make the UK a world commercial power again. “We are by instinct a great global trading nation,” she told a skeptical audience at the World Economic Forum (WEF) annual meeting in Davos last week. But you do not have to be a fully paid-up member of the global elite to conclude that her job will be very difficult, perhaps impossible. The days when Britannia ruled the waves — and the ports, industries and financial systems — are well and truly over. May has to have a plan B in response to her country’s pro-Brexit vote last summer. About half of UK exports went to member countries of the EU, and the tariffs that seem inevitable once Article 50 is invoked would put much of that trade at risk. Incidentally, it is noteworthy that the concept of “hard Brexit” has been replaced in the UK’s political lexicon by the much more benign-sounding “clean break.” That is a triumph for May’s spin-doctors, but amounts to the same thing. The cleaner the break, the harder the Brexit. A proposition for a protectionist White House: So instead, the UK is looking around the world to try to replace the trade that will inevitably be lost with the EU. May — and her International Trade Secretary Liam Fox — are already talking to members of the Commonwealth like Australia, New Zealand and India about a series of free-trade agreements (FTAs). May has also dropped big hints that China, Brazil and the Arabian Gulf countries had approached her with plans for FTAs. This week, she is heading to Washington for meetings with President Donald Trump to talk about a preferential trade deal with the US. In view of the new president’s vow to put “only America first,” you have to wish her good luck with that. It is hard to see her getting much out of the newly protectionist White House. If she did get a significant deal, it would be a relatively small but important step toward bridging the post-Brexit gap. About 15 percent of the UK’s exports went to the US in 2015; not enough to make up the trade that will be lost with the EU, but not to be sneezed at either. The “global trader” strategy is not without its merits. Even before Brexit, commerce between Britain and a number of non-EU countries was growing fast. Chinese and South Korean trade showed the biggest rises in foreign markets for British goods and services, with the United Arab Emirates (UAE) and Saudi Arabia also expanding faster than any of the EU countries (though from a much lower base.) Much has been made of the plans by international banks to relocate away from the City of London, but that will not be the UK’s biggest problem. London has many advantages over any other European capital in the financial sector, and any business that might be lost to Paris, Frankfurt or Milan can be compensated by London’s financial ingenuity. Britain’s real problem will lie in persuading the rest of the world that it has products worth buying at a decent price. Colonial power is history: When the UK was becoming an imperial power in the 18th century, it had some marketing techniques not available today. It was developing what was state-of-the-art technology of the day — engineering products and infrastructure assets like construction, bridges, roads and railways that the rest of the world badly wanted. It also had huge military power. The Royal Navy was the biggest and most powerful military asset in the world and was on hand to reinforce Britain’s commercial interests wherever they might be threatened. It also had slavery. Although the UK was among the first to make illegal the international trade in African slaves across the Atlantic, by the time it got its pangs of conscience in the early 19th century it had already amassed enormous fortunes through the slave trade. A cynic might argue that, in abolishing slavery, it was only pulling up the ladder from other trading nations who had not yet had the opportunity to make a fortune out of human misery. All those competitive advantages are absent now, as May tries to make Britain a global trading nation once again. Britain is no longer the workshop of the world, it does not rule the waves and the zero-cost labor option of slavery is no longer thinkable. You have to wish May well. She is trying to see through the practical consequences of an unexpected, but democratic decision. And if Britain becomes a force for economic globalization it can only be a good thing in this increasingly protectionist age. But the historical odds are against her, and her country.