I started sketching a large seabird playing a concertina one day. Things escalated from there.
The seabird gained a pipe peg-leg (the result of a cannonball shattering a nearby mast and a hurried amputation). He gained a songbird comrade. He gained bird-relevant nautical tattoos. I determined they were former sailors who had been forgotten by their navy.
The Pogues' tune "Misty Morning Albert Bridge" seemed to provide fitting lyrics.