Boris Johnson wrote in February that he would consider minimal checks on the border

Boris Johnson is facing accusations of hypocrisy after a letter leaked to The Times revealed that he gave his reluctant blessing to checks on trade between Great Britain and Northern Ireland while he was foreign secretary.

It comes after he flaunted his unionist credentials in an address to the DUP conference, suggesting that such checks would be unconscionable.

The Times has seen a three-page letter from Mr Johnson to Theresa May in February addressing Foreign Office work to try and explore solutions to the Northern Ireland border question, in which he said that checks between the province and the mainland might have to be considered. The DUP argues that any checks in effect impose a border in the Irish Sea.

“If necessary we could