IT HAS long been an article of faith for hard Brexiteers: there is nothing to fear from the World Trade Organisation. Many are suspicious of the compromises that a free-trade deal with the EU may entail, such as accepting its rules or even its courts. So why not just walk out and trade with the EU as other countries do, on WTO terms?

One answer is that Britain’s relationship with the EU is far more intimate than most countries’. The EU accounts for 43% of Britain’s goods exports and half its imports. In services, which make up 80% of British GDP and almost half of exports, the EU market is crucial. Theresa May has dismissed a Canada-style free-trade deal because it would mean “restriction on our mutual market access”. Shifting to WTO terms would be worse still.

It is also misleading to claim that the rest of the world trades with the EU on WTO terms. The Institute for Government, a think-tank in London, notes that all big countries have bilateral agreements on such trade-facilitating measures as customs co-operation, data exchange and standards. Hosuk Lee-Makiyama of ECIPE, a Brussels-based think-tank, says that only seven countries trade with the EU on WTO terms alone—and they are small fry like Cuba and Venezuela.

In any case, reverting to WTO rules is not simple. Britain was a founder of the organisation but now belongs as an EU member. To resume WTO membership independently will require a division of EU import quotas, notably for beef, lamb and butter. A first effort was roundly rejected by big food exporters like Brazil, Argentina and America. The WTO proceeds by consensus among its 164 members. Were Britain to leave the EU on acrimonious terms, negotiating its resumption of full WTO membership could be difficult.

Brexiteers say trade with third countries would be easier. Perhaps, but the EU has free-trade deals with some 60 countries, including South Korea and Mexico, and is negotiating one with Japan. It will not be easy for Britain to “grandfather” these deals, especially if it has walked out with no deal, if only because doing so would need EU agreement, too.

Then there is the WTO’s “most-favoured-nation” rule, which bars discrimination unless it is allowed by a fully registered free-trade deal. If after no deal Britain and the EU wanted bilateral trade to stay tariff-free, both sides would have to offer the same privileges to all WTO members. Services are barely covered by WTO rules. But even here, were Britain to seek to keep trade in services, the same terms would have to be given to several countries with which the EU has free-trade deals, including Canada. Subjection to WTO rules might yet prove more irksome than Brexiteers realise.