Celtic nationalism. But Scots, Welsh, Cornish and Irish people are not Celts, this has been proven with genetics and lack of archaeological evidence (no suggestion of a mass invasion of Celts).

These people have rich cultures and rich history. They want to revive their archaic languages because English is seen as the language of people who invaded them in the past.

First of all, Lowland Scots spoke a form of English through their relations with Northern England. Highland Scots spoke Scottish until the 18th century.

Secondly, the Celtic languages are also languages of invaders.

So what is the point? just stick with English, which should really be called British because the modern English language evolved through out the British isles.
No their languages died out, now they are trying to revive them.

Is that tradition? don't think so.
The Gaelic languages of the British isles are slightly different to eachother, that is why I say Scottish, Irish, Welsh and Cornish.

NO they are not descendant from Celts. As I said in the question genetic studies and archaeological evidence shows they are not celts... NOT CELTS

of the british isles.

I had an interesting conversation about 8 years ago with a visiting Scot. He confirmed for me that in Scotland's eyes-if you are born on this side of the Atlantic, you're not a Scot you're a yank.
That's always been the way I've thought of it.
I don't wakl around saying I'm Scottish, irish or Welsh when I'm not.
I'm an American. I don't even use Irish American or Welsh American. American should be all that's needed on the subject.
But two years ago, I talked this over with a student who had spent some time in Ireland and she said the opposite. That Irish Americans are regarded as Irish (or very close to Irish) in some parts of Ireland.
So I have Welsh, Scot, and Irish in my family tree. All cultures from the British Isles that are not actually Britsh are represented in my blood.
What do the Welsh, Scots, and Irish have to say on the subject?