Size does enter into it, if Scotland was way smaller it would be seen as less legitimate to become independant, because it doesnt rule that much to begin with. If it was twice bigger than England, there would be much more reason to become independant from GB because, hey they are puny we can rule ourselves easily.
Even geographical positioning is taken into the equation: islands are often way more prone to become independant, simply because they are not physically attached to a mainland and have mechanically more chance to have produced a different culture.
The relationship you are describing here is more the relative power of the two, the balance of power. Be that military, economic or the raw number of people. It's not the relative size that's important, even if they often correlate.
This is why Taiwan has such trouble with the mainland, despite being an island. It can never truly ditch China.
While Scotland could mount a very meaningful resistance, if UK ever forgot its western democratic values.
And if the internal power balance of UK was different and the pro-EU and liberal Scotland was in control, it would be the conservative England or Wales entertaining notions of ruling themselves more. And definitely not Scotland looking to break away from the union.
Legitimacy for independence and recognition as a sovereign state "in the club" and cultures are a bit more complex issues.
If the place is too small for a functioning state, it will of course have immense difficulty in being recognized. But even quite small groups can have a rather legitimate case for self-rule.
As to belittling Scotland in saying region, thats not really the point I wanted to make (I'm not interested in belittling such or such), United Kingdom is a country formed by several countries, you can label each one of the countries, regions and/or countries of the UK and not be wrong. If you want to prove that Scotland should be independent you might be saying "country" more, if against "region" but thats againt not what I'm trying to talk about
Yes, that's what I wanted to point out though. You communicate things with your choice of words, especially if there's a more accurate and relevant term available.
It wouldn't do to make a headline that says: "The woman Theresa May did this and that."
You of course say: "The British PM Theresa May did this and that."