I know this is an old thread - but I just discovered this amazing song and wanted to know more about it.

I found this:
http://www.hymnsandcarolsofchristmas.com/Hymns_and_Carols/world_is_old.htm

Houseman was correct! And the music was by Joseph Morrat.Source: Martin Shaw and Percy Dearmer, The English Carol Book, Second Series (London: A. R. Mowbray & Co. Ltd., 1913), Carol #50.