There is an attitude among Remainers that regards the EU's customs union as a comforting thing. It is, they seem to think, a benign economic version of Nato, keeping us safely inside a warm embrace.

Of course it is nothing of the kind. Any benefits of "frictionless" trade with the EU are completely negated by its own protectionist barriers. Goods sold within the EU are 20 per cent more expensive on average than market prices outside, because tariff walls allow internal producers to bump up their prices.

Free trade with the rest of the world, conversely, would not only reduce the prices of non-European goods by removing these tariffs. It would also force European sellers to reduce their prices to compete with global competitors, so providing cheaper produce for all consumers.

It was for this reason that the Conservative manifesto last June – securing the highest number of votes for 25 years – clearly promised that the UK would "no longer be a member of the single market or customs union." For the good of every citizen in the country and the integrity of our democratic institutions, that promise must be delivered.

It is now reported that the UK’s proposed plans for the so-called "Irish backstop" – whereby, if no trade deal is achieved, we will maintain "full alignment" with whatever EU regulations necessary to maintain a soft border in Ireland – put no time limit on this option, and do not permit the UK to leave it unilaterally.