It's not really...

It's not really a Christmas song.  It's a Boxing Day song.  The king is hiding out to help out a subject on the bottom rung of his kingdom's social ladder.

Still, jolly ol' King Wencey might have been a toff, his heart appeared to be in the right place.

The origing of Boxing Day are unknown, though personal conjecture makes me believe the story of Wenceslas couldn't have hurt any in the tradition's formation.  I mean, St Stephen himself has the feast day, but his proto-martyrdom wasn't about bring forth blessings to the poor and lowly.

When he lived, in the 900s AD, he was only a Christian once removed.  That part of Bohemia was still quite pagan.  He died because of worldly political intrigue, and with a hint of ecclesiastical struggle with them selfsame Pagans.  His brother was the bad egg that did him in with Treachery.  Red Wedding style.