The Good Friday agreement is under threat – but it’s key to resolving Brexit

It is precisely because of such issues as the border that there should be a confirmatory vote on whatever now emerges from the Brexit process in parliament. The Irish border question is a metaphor for the entire negotiation. It is not possible for the UK to have frictionless trade with the EU if it remains outside the single market, so the question is how much friction is compatible with the Good Friday agreement, and that in turns defines any Brexit agreement that will pass through parliament.