Three of the UK’s four nations are led by parties advocating a split. Which is most likely to go?

For the first time in its history three of the four nations of the UK are led by parties that advocate holding referendums on breaking away from the UK.

Recently, the first ministers of Scotland, Wales and Northern Ireland signed an agreement to work together on this agenda. (Michelle O'Neill did so in her capacity as vice president of Sinn Féin rather than as Northern Ireland’s first minister, as that office is held jointly with the DUP).