Question for British Folk and/or Smart Dudes and/or Ladies

[Nate the Great]

In the sixteenth century I don't think any of those called themselves separate countries, at least not in earshot of England.

So I wandered over to the Wikipedia line of succession page, and found it most interesting.

1. There are way more kings and queens still "active" in Europe than we think.
2. All of them are somehow in the lines of succession for each other.
3. The rules about who can be king are very strict.
4. Somebody has way too much time on their hands calculating this stuff, because there are thousands of entries that will NEVER be King. They'll be dead before the list works its way down to them.