Lord Lilley is a former Secretary of State for Trade & Industy and for Social Security.

Critics assume that, but for the Protocol, the UK would introduce border controls and checks on trade with the Republic.

In fact, the only party threatening a hard border on the island of Ireland was the EU.

The EU claimed that (unless the UK kept either Northern Ireland or the whole UK subject to EU internal market and customs law) it would need to apply along the border between Northern Ireland and the Republic of Ireland the full panoply of border checks and inspection posts normally specified in EU law.

These checks, it said, are necessary to protect its Internal Market from goods entering the EU which do not meet EU specifications and pay its tariffs – and might therefore either threaten the health of its consumers or compete with its producers.

By contrast, the UK has repeatedly said, in the words of Jon Thompson, the head of HMRC: “we do not … require any infrastructure at the border between Northern Ireland and Ireland under any circumstances [even if the UK left on WTO terms].”

HMRC (and DEFRA) are confident that they could enforce UK regulations and standards on goods entering the UK from the Republic without infrastructure and controls at the border. Pre-Brexit, they already policed differences in VAT, excise duties, red diesel, as well as trade in drugs and weapons without resort to controls at the border. Any checks needed were carried out by inspecting the company’s books or goods at the point of despatch or delivery.

Initially, Niall Cody, the Head of the Irish Revenue was “practically 100 per cent certain” that there will be no need for new customs facilities along the border. And the then Taoiseach, Leo Varadkar, said: “I’ve made it very clear to my counterpart in the UK and also to all the other EU Prime Ministers that under no circumstances will there be a border – full stop.” “In terms of a no deal scenario … we won’t be installing a border between Northern Ireland and Ireland, and everyone knows that.”

That changed once the EU insisted that its laws required border posts and checks – unless the UK applied EU laws and customs checks in Northern Ireland or the whole UK. Irish Republicans then realized this threat could be a stepping-stone to a united Ireland. And elements in the British Government were happy to use it as a lever to keep the UK within the EU Single Market and Customs Union.

Nonetheless, had the UK not bowed to the EU’s threat that it would build a hard border if the UK did not implement its laws the other side of the border, neither the UK nor the Irish Republic would themselves have created a hard border.