BREXIT is often like reading a good book, where you never see the twists and turns coming.

Those who voted remain will say they warned of problems ahead, while many who voted leave will now privately admit they never believed the process would become so complex. This is no surprise, given that we have been tied into European policies for the past 40-plus years.

Twists are now so common that we are left wondering where they will lead and what will be next. The latest is that Scotland and Wales are considering legislation to hold on to powers in agriculture and food now administered by Brussels. They want to cut London out of the post-Brexit equation in these areas. Whether they succeed is not the point, although they have a strong case based on the importance of agriculture and food in the devolved regions in comparison to England.

It is worth remembering that just last week, the Chancellor, Philip Hammond, suggested UK fisheries interests could be bargained away with Brussels in return for maintaining a single market for financial services. From a UK perspective that might make sense, but it is a slap in the face for an industry that voted for Brexit for sound business reasons.

Whether it succeeds or not, the devolution threat over legislation is another challenge to the already difficult Brexit political process at Westminster – although to be fair the Welsh have less of a case, given that unlike Scotland, the majority there supported leaving the EU.

When people are playing political games, they need to remember the risk of making a bad situation worse. It is unlikely the decision to leave the EU will be changed, so the name of the game has to be making a success of the outcome, while minimising the economic damage. Even those committed to Brexit admit the economy will take a short term hit, and the government cannot forever pay more to Brussels to head off difficulties. Get the trade issue right and this would solve many of the economic challenges Brexit will bring.

That means wise rather than political heads prevailing. We need to get away from the delusion that we can have pain-free trade deals with countries outside the EU, or that they are lining up and happily accepting that we do not want their food because we want EU quality standards.

Ask any business, and they will confirm that trade works best when you sell into your closest market that offers good prices. That is why Ireland's biggest food export market is the UK – and it is why we have done, and are still doing well, selling into the EU-27.

Profit comes from good prices for high quality food, rather than commodity markets, and from minimising transport costs and avoiding duties. That is the attraction Margaret Thatcher saw in the EU single market when she was one of those driving its creation and efficient working.

Trade will be central to whatever deal finally emerges between the UK and EU. There is lots of hot air around from the European Commission and parliament, but heads of state and other ministers from the EU-27 member states know that pragmatism is needed.

This, like most things in life, comes down to financial realities and the need these countries have to maintain trade links with the UK. Strip away the political rhetoric and when it comes to food we are in a mutually assured destruction mode, where a hard Brexit would be a disaster for both sides.

A recent report put at £9 billion the cost to agriculture and food of a hard Brexit. No such report is ever more than a forecast based on set conditions. But the point with this report is that it underlines that of that cost, £6 billion would fall on the EU-27. Tariffs on imports to the UK would be a disaster for key member states, including the Netherlands, Ireland, France, and Germany.

This can be confirmed by a look along any supermarket shelf. For the Dutch, a hard Brexit would be a 2% or £500 million a year hit for its farming and food industry. Ireland's biggest export market would suffer a blow that would be felt across the entire economy. This is why common sense has to prevail over politics – and that is as true in Dublin or Berlin as it is in London.