NOBODY doubts nowadays that foot-and-mouth disease must be controlled and eradicated. When it occurs, most often in cattle but also in other farm animals, it gives the beasts baneful blisters and high fever, making them unfit for human consumption. Because it spreads at great speed, the usual method of control is the slaughter of entire herds round the locations of the outbreak, whether or not infection in each of them has been proved.

Yet there was a time when none of these seemed to be the right sort of reaction. In the modern period, the first big epidemic came in 1865. It spread rapidly through Europe and reached France which, then as now, had a huge agricultural industry, with a lively trade across the Channel to the UK.

Sitting in Number 10 Downing Street, the Liberal Cabinet of Lord Palmerston felt not at all sure what to do. While a ban on French imports was being publicly called for, the ministers felt this would go against one great political principle they all fervently favoured, the principle of free trade.

It was less than 20 years since the UK had led the world in abolishing taxes and tariffs on imports from abroad. Those years saw the problem of how to feed the new industrial working class solved. The prosperity of the Victorian era opened for everybody. Could the free trade that had made this possible now really be abandoned?

To recall such an obscure episode in UK policy-making is to remind ourselves that some aspects of it do not change. One basic fact about these islands is that they cannot feed themselves. They, therefore, have to find means of maximising their non-food production to exchange for the food their citizens need to eat. Whether or not Boris Johnson realises as much, it is a question of no less importance for him than it was for Lord Palmerston.

Two centuries ago, the question had been answered by the repeal of barriers to trade. Today, the question is posed anew by the UK’s decision to leave the EU. In Victorian times we found a long-term answer. Can we now do the same again for the 21st century?

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It’s a big question and the answer, or rather answers, will be dauntingly complex. Luckily, they are at this moment being distilled by a particular controversy that any of us can follow, the one over chlorinated chicken from the US.

Top of Boris Johnson’s commercial priorities is a trade accord with Donald Trump, so the vast US market can be opened up to UK goods, and especially services, on a scale that will more than compensate for what we may be about to lose in Europe.

Trump prefers bilateral agreements with single countries to the sort of give-and-take typical among global blocs of trading nations bound by strict rules. Almost the first thing he did on entering the White House was to end American membership of the Trans-Pacific Partnership, in which he claimed his country was being taken for a ride by the wily orientals.

Now he wants the UK to drop the EU’s ban on imports of American chicken that has been in force since 1997. Long the object of intensive lobbying in Washington, it would be symbolic of a much wider new relationship between the two English-speaking economic powers.

The National:

To the US, agricultural trade appears the obvious place to start constructing this new relationship. It is, for example, the world’s biggest breeder of poultry. Nearly one-fifth of its production is exported. Lower hygiene standards make its chickens the cheapest on international markets, even while they come to us carefully prepared and packaged.

Whereas the US has a massive surplus of farm produce, the UK has followed a course of fitting into the EU’s Common Agricultural Policy by going for high quality in specialised lines – now worth £7 billion a year, so by no means negligible as an export.

IN other words, our UK market does not seem to be one in which chlorinated chicken will easily fit. At least for a transitional period, we will stick to the stricter regime of European regulation so as to achieve a superior result in terms of foodstuff quality. But the American method is cheap and the European method is expensive. Therefore, once we finally leave the EU it should be possible for American chicken to win a larger share of our UK market.

More to the point, US agriculture has been nothing like as closely regulated by the federal government in Washington as European agriculture is by the EU Commission in Brussels. Across the 50 states, the abattoirs for slaughtering the wretched chickens get dangerously filthy with the offal and excrement that squirt out of them. Americans solve the problem by at once rinsing the edible flesh in disinfectant chlorine to kill the toxic bugs they may carry.

In the UK, most of us associate chlorine with cleaning the toilet rather than cleaning food. Yet persuading our negotiators to drop the existing ban and accept US standards is in Washington a high priority for a trade deal.

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To survive the fresh competition, many of our producers would need to lower their standards, too. This cheap food might also be exported to Europe in the transitional period. Here is the reason why in Brussels they propose the UK should maintain European standards indefinitely. The chief EU negotiator, Michel Barnier, has put chicken at the top of his list of detailed points due to be settled in the negotiations now under way.

Of course, the battle is about much more than chlorinated chicken. This particular US agricultural export keeps rearing its head because it sums up far broader arguments about the future of relations among the different trading blocs.

For Americans, one prize of Brexit is the chance to break open to its agricultural surpluses a major European economy. The US has suffered years of failure in trade talks with the EU, which refuses to weaken its food and farming standards just because the other side cannot live up to them.

The EU takes a different view to the US on food safety. It applies the precautionary principle, banning substances and processes that are potentially harmful till they are proved to be safe. The US tends to accept chemicals till they are proved to be harmful. It sees the EU objections to its goods as at bottom protectionist.

British farmers know that if US imports of cheap but potentially unhygienic meat are allowed, they could face ruin. The European industry fears the same. Johnson needs to be clear how voters might weigh up consumption versus welfare, especially during Brexit.

The UK cannot have it both ways. And it is another area where plausible bluster will never make up for unsound policy. As a previous victim of coronavirus, Boris can hardly afford a second lockdown.