Other way around then? Is a consonant, but a defacto vowel? Whatever, English is weird.

Why do you say it's a de facto vowel?

It isn't used like a vowel. There's no word 'XwY' for any string of letters X,Y - and you can't prounounce 'xwy' (for any single letters x,y) without adding vowel sound.

I suspect in the sense that 'w' acts like a long vowel or a diphthong in many cases in English when it is used in the middle or at the of a word.

E.g., (spelling vs pronunciation) 'town' vs 'toun', 'own' vs 'oan', 'bow' vs 'bo' or 'bau', etc.

It definitely seems like the most vowel-like consonant after 'y'.

'Semi-vowel' seems to be the word, for 'y' too.

https://en.wikipedia.org/wiki/Semivowel

> There's no word 'XwY' for any string of letters X,Y

Awe, ewe, owe, awl, owl, own, two...

But my point was that in all other European languages, the letter 'W' is clearly a consonant, usually realized as [v] or [ʋ], and seen as a variant of 'V'.

English is the odd one out, English sees it as a variant of 'U', and it's not clearly a consonant, it's a semi-vowel as you pointed out further down.

Right, I meant consonants, not 'any letter'. (You could do examples like that for any consonant in place of 'w'.)