IN the autumn of 1865, the UK faced a potential food crisis.

A horrible infection of cattle called rinderpest (now eradicated, but much like foot-and-mouth disease) had spread from central Asia all the way to France. In Downing Street, the Cabinet needed to decide whether to ban agricultural imports from across the Channel. Eventually they did, but only after prolonged heart-searching.

The prime minister at the time was Lord John Russell, a rebel aristocrat known as Radical Jack for his championing of popular causes. This was mainly because he had written the Reform Act of 1832, which set his country on the road to democracy. Like all Radicals, he was an enemy of the great landowners who still dominated the countryside. He had robbed them of their political power and he wanted to rob them of their economic power, too.

Russell did this by supporting the repeal of the Corn Laws in 1846, which meant the big landowners got no more agricultural protection to maintain their incomes. Instead, free trade would make bread as cheap as possible for the urban masses while the UK turned into an industrial nation. It was a far-sighted move which did as much as anything to ensure this would be a peaceful and not, as in other countries, a revolutionary transition.

But, like many UK politicians, Russell forgot about Ireland, which had little industry. When the Great Famine struck there, he thought the free market offered the solution. It would supply the food the peasants needed after their potatoes had all been blighted. So when the richer Irish farmers continued to export produce to the lucrative English market, the government refused to intervene. In fact it halted relief schemes already in operation on the grounds they would encourage idleness among the starving.

The same dogmatism was still at work when the rinderpest threatened in 1865. Free markets were good for British industry, by now conquering the world. Why not for agriculture too? Russell had huge difficulty in sorting this question out in his own mind, which is the reason a man who might have gone down as one of the best prime ministers has instead been forgotten. At the time, his cabinet made him see sense.

More than 150 years later, we can remind ourselves how some political problems never go away – in the present case the conflict between the call from customers for affordable food and the need for an adequate revenue in the finances of farms.

The net result of collective experience in advanced countries over this stretch of time is that nearly all subsidise their agriculture. Without that, a great deal of Scottish agriculture, for example, would just die out.

After Brexit, will support from the UK turn out as generous as support from the EU has been?

I doubt it, but until a crunch comes we stick by the policy that stable supply is the paramount requirement in an industry doomed to instability through the vagaries of weather, consumer taste, scientific advance, international markets and so on. Taxpayers’ money is what buys it.

More predictable is that politicians seek to exploit the symbiotic relations they build up with farmers, and that these in turn capture the political process so as to turn it to their own advantage. Last week this murky business took on human form when the US ambassador in London, Woody Johnson, urged post-Brexit Brits to switch to a diet of chlorine-washed chicken and hormone-fed beef, supplied by Trump’s America.

This might clinch a key trading deal to be negotiated between the two English-speaking nations, and in a new era drive a wedge between them and the effete Europeans.

READ MORE: Brexit could mean a return to food rationing

The EU, Johnson said, was a “museum of agriculture”. But it is the US that has constructed a museum. The federal government does not have the internal powers that any European state takes for granted, and is unable to enforce regulation on every inch of a country 3000 miles wide.

It houses two million farms, more than half of them small farms of less than 100 acres. And one in 10 is a chicken farm. Out on the Great Plains – Iowa has the most – chicken farmers do their own thing. They often curse Washington but then call on politicians to cushion them when they need it.

Which brings us to chlorine. The chicken farms are filthy. Jerry-built as cheap as possible, they let in no light or air for the birds they briefly house. These chickens are crammed into cages where their feed is carefully calibrated. Their only purpose in life is to fatten up for a few weeks before they are slaughtered. The deliberate overcrowding means they cannot flex their muscles, and their flesh remains soft.

Their fear and stress still make them attack each other, so they are debeaked. Some farms rear 100,000 of the wretched creatures at any given time. They are cesspits of salmonella, a sickness spread to humans by animal faeces.

Chlorine is a disinfectant. That is why it is the first thing you smell on entering a public swimming pool, put there because swimmers pee in the water. The reason American chickens are washed in chlorine is that otherwise they might make the humans who eat them sick, or even die.

They are, all the same, banned in Europe – and no wonder when you go into the detail of the production.

The maximum freedom of markets historically favoured in America (if no longer in Trump’s America) has been a fine thing for Americans. But it has its limits anyway and if it is a matter of human health and safety, all nations agree we do need to intervene somewhere. The basic difference from Europe is that on our side of the pond the intervention comes before rather than after the death of the chicken; in fact, it follows it from egg to knife.

It is true the EU is constantly tempted to over-regulate things and, for every food product, insists on minute labelling of contents.

I never read the list on the packet, but all the same I’m glad it’s there. To ambassador Johnson and his boss the UK should say, when the time comes, that we will continue to prefer hygienic European chickens to whiffy American chickens.

On beef, the issue is less clear-cut. Hormones are fed to American steers, that is, to castrated cattle.

The treatment restores their manhood (or bullhood). Their feeble flabbiness turns to lean and muscly vigour. But its effects on humans who eat the meat remain as yet uncertain. In this case, the EU policy is to err on the side of caution: we will not buy these beasts till it is proved they cause us no harm.

That is also a sensible policy for the UK to maintain.

Presumably talks for a deal between the UK and US will start up as soon as possible after March 29, and in Washington a game plan has already been unveiled for removing the barriers to transatlantic trade in agricultural produce.

The aim is to “eliminate practices that unfairly decrease US market access opportunities or distort agricultural markets to the detriment of the United States”. Let us hope the actual negotiations will not turn out quite so one-sided. But after the UK’s incompetence in Brexit we can never be sure.