King Arthur - Fact or Fiction?

Tinwheeler

I was looking through some old pics taken at Trewethett Farm, Tintagel earlier and it made me wonder about King Arthur.  Do you think he existed either as folklore would have us believe with all the romantic tales, or just as a leader defending Britain,
or is everything pure myth?  I confess to not knowing that much about him as tends to happen with local stories as you grow up just accepting what you hear without delving deeper.