Duties of Customs

If we are outside the customs union, it suggests that there will be a hard border, but if we follow the Government’s logic that that will somehow be mitigated and we will have an open, frictionless border, surely the border will simply have to be around Great Britain—it will have to be at the Scottish and Welsh ports. Does the right hon. Gentleman agree that if Northern Ireland is treated separately, that will cause a constitutional problem?