I must say hat I found Dan Worrall's evidence pretty persuasive, though it's clear that it wasn't just concertinas. Quite a few banjos, as I remember - anything that was cheap, really. In the case of a concertina, cheap and loud, which would be handy in a maritime setting what with all those howling winds, creaking sails, cursing sailors, cackling parrots, and the chink of pieces of eight.