It’s make your mind up time: the cabinet has to decide what form of customs relationship it will seek with the European Union.
Downing Street’s position is that while we will not be part of a customs union with the EU a la Turkey we will be part of a “customs arrangement”, which is pretty typical of the Theresa May approach to Brexit: make a lot of noise, then agree to the same deal but with a synonym in place of the offending word. See the transition (sorry, “implementation”) period, the deal over the Irish border, the divorce bill and so on.
The difficulty for the government now that is that while most of the Brexit ultras have been bought off so far by running offending documents through a thesaurus, one politician who has, whatever his other faults, always understood the implications of the government’s position is Jacob Rees-Mogg, now head of the European Research Group. Simply calling the new arrangement “a customs partnership” might not be enough to keep the Brexiteers on side.
That said, Leave ultras might already be too late. As far as customs go, the British government has already agreed a very close degree of alignment with EU regulation if its promises on the Irish border mean anything. That said, Leavers may think that, at this point, one more broken promise is a price worth paying for the “correct” Brexit. There is also a view in Leaver circles, and not one entirely without foundation, that come the crunch, continuing co-operation in security, counter-terrorism, scientific research and numerous other areas will mean that a hard border on the island of Ireland is a price that most EU member states will be willing to pay. If it’s not, then “no deal” might still be on the table.