Can a member nation of the united kingdom withdraw from the union?

Question

what would happen if wales, scotland, n. ireland or england simply said, i quit? what advantage is it to each nation to remain in the uk? is it a completely voluntary association?

Answer 1

as a exbrit the union was formed by conquest long ago,England cannot opt out as they are the concurees,the others can vote for home rule i think but defense and external matters would stay with London,

Answer 2

Every member state of the European Union is bound by the principle of self determination. So if a majority of people in Wales or Scotland voted for independence the UK government would have to allow it.

Answer 3

Well Wales joined England by conquest - part of the peace treaty was that the first born son of the monarch would be Prince of Wales.

Scotland and England ended up with the same king eventually, and later their parliaments passed an act of union. As part of this Scotland retains its own separate legal system.

Ireland and UK also passed an act of union resulting in Northern Ireland joining.

So it is not voluntary - there is a legal framework

In theory any of the countries could declare independence. Recently regional parliaments have been set up again. One inconsistency is that  there is no English parliament - the UK one serves that purpose, so Scottish MPs vote on laws that only relate to England, but as English MPs are not members of the Scottish parliament they don't vote on laws that just affect Scotland.

Advantages perhaps that resources are shared. Historically England was richer, although in recent years Scottish oil is a factor.