TRADE WILL be the biggest challenge of Brexit. That is accepted by the business community in the UK and in much of the EU-27. 

The UK trade secretary, Liam Fox and some other Brexit advocates in the Cabinet, insist this will all be sorted and that people are worrying needlessly. The food and drink industry in Scotland will be hoping their optimistic view is correct, but I would not like to bet on that outcome. 

However, by continuing to invest in their businesses, from the smallest farm to the biggest food processing plant, people are doing that every day. The risks they are taking need to be recognised by the government with more than bland assurances that everything will be alright.

If there is no certainty about the future of farm support, there is even less about trade. We have heard ministers promising that the UK will lead the way on global free trade by having the lowest possible tariffs, in the hope that others will reciprocate. 

The big prize the government wants to hold up as evidence that Brexit will work is a trade deal with the US. This has proved difficult for the EU to achieve, mainly because it will not reduce its standards for US imports, including food. The government, however, had a big boost when the US commerce secretary, Wilbur Ross, said the UK could have an almost instant trade deal with the US.

This comes with a big caveat. Securing that deal, which the government desperately wants, would mean the UK would have to lift its opposition to American imports. He cited two products where rules would have to be changed. Those were the import and growing of genetically modified (GM) crops and the import of chlorine-washed poultry. 

The message from the US commerce secretary was that the UK must not let a desire for a trade deal with the EU-27 dictate its policies on food imports. This ignores the reality than many consumers in the UK do not like these technologies. 

This is not because there is anything wrong with them, but they have been demonised to the point where they are as unacceptable in Britain as in the EU-27.

This leaves the UK in the position of someone playing cards, who has to discard one of two good cards to continue in the game. The US offer is attractive, but of limited benefit to food and farming, since the US is more interested in exporting than importing, beyond specialist products.

However, a well-performing US market is a big one for the wider economy, with less regulation than many alternatives. 

But on a head count basis, the EU-27 is a bigger and growing market in terms of population. It is also the one with which we are used to trading and is, of course, our nearest market. It will demand that post-Brexit UK food and farm products coming into that market will match the rules farmers there have to meet.

We should expect nothing else, since those are the rules we have gained from for many years as members of the EU. It will remain deeply suspicious of GM and chlorine-treated poultry, no matter what science says. This is the prerogative of the EU and it is a stance largely supported by consumers. 

Much as the government in London may want to tell the EU what to do, it is not going to change policies it believes are popular to accommodate a country that decided to leave the club. If we are to continue exporting into the EU, we are going to have to accept some ‘either/or’ choices. 

That is a fact of life, whether you are walking away from a trade bloc or a golf club. The other members are going to go on doing what they do, regardless of your decision.

When it comes to trade, some tough choices lie ahead. Neither the UK or EU will gain by cutting off their nose to spite their face. The EU-27 wants to continue selling food, BMWs and wine into the UK and we want to continue buying them; we want to continue selling food, cars and Scotch whisky to the EU-27. 

Anything else is nuclear war style ‘mutually assured destruction’ of their respective economies. That should be central to the debate in London, more so than a politically attractive but economically less important trade deal with the US.