The value of the customs union to the UK is overrated | Larry Elliott

It's seen as a key part of a soft Brexit, but in reality the union has not provided much of a boost to trade of goods with the EU

The Corn Laws. The tariff reform debate of the early 20th century. Imperial preference in the 1930s. There have been times in Britain's modern history when trade policy has really mattered, breaking parties and swinging elections. To that list can now be added the question of whether Britain should be in a customs union with the European Union.

Business certainly thinks so. Leaving the customs union would give Britain freedom to negotiate its own trade deals but this, according to the country's most powerful employers' organisation, the CBI, is not why people voted for Brexit. That was primarily about money and immigration rather than a desire for the local supermarket to be able to stock hormone-treated US beef.

Customs unions or trade liberalisation deals matter a whole lot less than the underlying shape of an economy

Related: Is May's offer to Labour sincere? Here's why the answer is probably not | Tom Kibasi