> You get the DUP to agree to that and I'll buy you a pint!!

Raggy, the DUP can say what it likes. According to my understanding of the Good Friday Agreement, the call for a border poll doesn't require British Parliamentary consent, just the advice of the Secretary of State for Northern Ireland (in the absence of Stormont), if he or she has cause to believe that it's the popular will. It's a government issue, not a Parliament one, so all the PM has to do is accept the judgment of the S of S, and proceed to put a border poll in motion. And if the PM refuses, it probably wouldn't happen. But if it gets denied in the event of a hard Brexit, seven kinds of hell will probably break loose, for financial reasons more than political ones.

[The DUP's] insistence in remaining part of the UK has never featured strongly in people's minds; rather it has been a case of economic security... Brexit has driven a Chieftain Tank through that one.

It'll drive a tank through the Protestant farmers/small businesses vote too, when election time rolls around, which the DUP would do well to remember. As Jim has indicated, people are more worried about being able to feed their children and keep up mortgage payments than ideologies.

Of course, reunification also needs the consent of the Republic of Ireland, which can only be obtained by putting it to the vote here, i.e. a referendum. If both nations then find for reunification, the legislation is already in place (AFAIU) to implement it.