I've been too busy to take part in that debate, but I see that this has in any case been pre-empted by User:Kotniski who has created and populated the ":Category:Constituent countries of the United Kingdom". In my opinion this is unacceptable as 
1) the debate mentioned by Dai is still in progress, and
2) the new category name has the rejected term "constituent countries" and is therefore contrary to a decision reached after a long discussion and contradicts the main article's name (Countries of the United Kingdom) and the term found in most other relevant articles. 
Personally, I don't see why Wales et al should not be categoried as 'European countries'. I am certainly against this unilateral reversion to a contentious and rarely used term that has been rejected here. I'm also somewhat suspicious as to what is going on here. This all started as the results of edits by a "new" contributor, TDSDOS (who seems remarkably familiar with wikipedia editing and terminology) whose few edits thus far are mainly concerned with the status of the three countries of Britain (and a bit of Ireland). Then we have the unilateral creation of this category. Am I the only one who thinks this is more than fortuitous? Be that as it may, this new category is not acceptable and a consensus decision would also be needed for the logical alternative, i.e. 'Countries of the United Kingdom', if the need for it is proven and accepted.