Often drunkenly and badly, but that's infinitely better than not at all. And the "Anacreontic Hymn" was probably mostly sung by drunks.
The rest of 'em were singing "The Ball of Kirriemuir" or "The Sea Crab" or equivalents. "The Bastard King of England" is of relatively recent vintage.
I had a standing invitation to dinners with the local Rugby Club because I knew all those songs, words and music, including of course "The Rugby Song".
This was in my life B.C. . . . Before Children. My kids have no idea I know all these things.