Not putting him down, Joe. I think he's evolved and is just catching on to it.
Note... "- and with his own compositions, which are most definitely in the traditional idiom."
A traditionalist would never make such a statement.
Not even in Leeds.
What you and I see from our different vantage points will obviously not be the same. That's Paradigms.
Duncan however is questioning where he is in relation to his surroundings. Something entirely different. Clearly he considers himself as Trad yet even his own bio spends more time on other genres and artists than Trad.

"He sings traditional songs as the bulk of his set" is all he says about the Traditional music in his arsenal.
Naw. He's a singer songwriter and probably a good one but he's just coming out.
Check him out folks.