HMRC boss warns Brexiteers' customs plan 'would cost business £20bn'

The boss of HMRC has told MPs the post-Brexit customs option favoured by Brexiteers would cost businesses up to £20bn per year.Theresa May's Brexit "war cabinet" is divided in its support for two different options for when the UK leaves the EU's customs union.The prime minister has ordered her top ministers to split into two groups to work on the competing models.