Steve - you've just confirmed the datings I gave in my original comment! Is the Saumarez text published anywhere, btw? Always been intrigued by that younger brother - I read somewhere that the original line was (in the voice of the captain) "if it had been my younger brother, this battle would still have been tried", or something along those lines.

Anyway - where's the indisputably 19th-century song of whaling/piracy/etc, that's the question. Flash Lad: 18th century. Bill Brown: 18th century... Aha! The Poor Murdered Woman: 1834. So there's another.