THE DEBATE about whether, after Brexit, the UK should remain in some form of customs union with the EU-27 will not be easily solved.

Such an arrangement would suit agriculture well, but it is now the stuff of high politics, and is at the centre of the battle in the Conservative party over Europe. This was meant to have been solved by the referendum, but it is now worse than ever.

Like everyone else, farmers are bystanders to this fight over their economic future, but it is the EU that holds the trump card. The UK agreed last December that there would be no border between Northern Ireland, as part of the UK, and the Republic of Ireland as an EU member state. If this cannot be achieved through technology there will be 'regulatory convergence', which means a customs union.

All the ideas put forward by the UK have been rejected. The idea of a special arrangement for Northern Ireland alone to have regulatory convergence has been rejected by the DUP, which is propping up the government at Westminster. That favours a customs union, but whether that is deliverable politically by Theresa May is very much in doubt.

In a debate on the customs union idea, Conservative MEP Daniel Hannan warned, rightly, that being in such an arrangement could be worse for the UK than remaining in the EU. This was on the basis of the responsibility without power to influence decisions argument, which is a valid point.

What is worrying for agriculture is that he criticised Labour for supporting the customs union idea, because the poorest in society would pay. This claim was based on a continuing link to the EU-27 denying consumers lower food prices. It is certainly true that this is the group that spends the biggest proportion of their income on food, but the key question is why he believes leaving the EU will drive down food prices.

Food prices can only fall under these conditions for one reason. That is if the government reduces or eliminates tariffs on food imports as part of the trade deals it is desperate to secure to prove Brexit can deliver for the UK economy. That would certainty drive down food prices, and it has been the danger of Brexit for farmers since the process began.

We have heard claims, but not guarantees, from politicians – including Michael Gove – that food imports will have to match UK standards. However such assurances are meaningless without legislation. The mindset in government is around tariff elimination and free trade, and food is part of that equation. The gain would be for the majority, while farmers would be bought off with environmental payments.

Ironically this runs counter to research on the impact of a hard Brexit and the imposition of default World Trade Organisation tariff rates. These would drive up the price of food in the UK, to the benefit of farmers, because food from the EU-27, which dominates the market, would become more expensive.

Welcome as that would be for farmers, the government cannot afford to allow this to happen. A negotiated exit from the EU with a soft-touch deal to trade with the EU-27 would maintain the status quo, but this is becoming a less likely outcome.

The EU-27 holds the trump card of the Irish border issue and it favours a customs union. Brexit advocates want tariff free trading with the rest of the world, and it is hard to see how that could ever go hand in hand with any form of negotiated deal with Brussels. The fear would always be that food would be imported, packaged in the UK and then sent into the EU-27. The prospect of this back-door trade to get around EU tariffs would be used against all UK food exports, by those in the EU-27 who would be happy to see their competitive position improved by the absence of UK competition.

The complexities of trade are also why farmers could end up after Brexit with more, rather than less regulation. They will have to comply with the new rules for the green Brexit and with EU standards if there is trade arrangement to access to the EU-27.

The same would apply to imports, but the big question is whether the government's priority is to protect the farming industry and food quality or to deliver supermarkets shelves full of cheap food of uncertain origin.