[A Navy Vet]

"But if the United Kingdom were to quit the EU, “there will be a border again between Ireland and Northern Ireland. And that could at least have the potential of rekindling a conflict that has seemingly calmed down,” he said. …"

Why would there be a border? Couldn't England just leave Ireland alone and still quit the EU? I have no knowledge of the Irish/English conflicts. Please explain.

[River Hawk]

Because Northern Ireland (Ulster) is part of the United Kingdom, not the Republic of Ireland. Currently both the UK and the Republic of Ireland are parts of the EU, and there is an open border between Northern Ireland and the Republic of Ireland. But if the UK (which includes Northern Ireland) withdraws from the EU, that could change.

[Undecided 2012]

England could exit and negotiate a deal for free passage with Eire. I look at it as a benefit for the Brits because it forces France to secure their border at the chunnel and Calais keeping the illegals out.
Brexit is a win for the English. Not sure about the Scots