You could turn the thread name round the other way..

The obvious Vaughan Williams use of traditional tunes he collected which were weaved into themes (and when he was commissioned to write A Pilgrims Progress Music, hymns...)

Tchaikovsky’s theme from the 5th used by Bill Caddick is mentioned above but Tchaikovsky got that from a street player in Italy when he was on his “grand tour.”

We can never know how composers in the past developed particular melody but there are enough examples around to show that many were borrowed from tunes being played in towns and villages through the ages, or traditional tunes as we say now.

I live near Epworth, the home of the Wesleys. I’m doing a bit of research as I’m sure that some of the tunes Charles Wesley set hymns to must be ones he heard locally with other words. It’s tempting to dig out Child and say that tune fits that ballad but I’m trying to find local words that may be more than a coincidence.