To return to the thread title, someone suggested that the song was scarce.Under that title perhaps, but Roud 511,Laws K40, master title, Jack the Jolly Tar, exists on numerous broadsides under various titles, and if we are to go by the widely differing versions in many publications, it was once very popular in oral tradition. Bert would have had a whole host of sources to cobble his version from, e.g., Sharp has at least 4 versions from this country. I think Peter Bellamy also rewrote it and called it 'Yarmouth Town'. It's also quite popular in North america.