I learned it from someone at Dorchester (UK) folk club in the 1960s (my memory says it was from from Sarah Morgan, long before she was part of Craig, Morgan,Robson) I've never heard a recorded version and assume that, as is so often the case, I learned the melody and first verse from a club singer and then found the words in a book. I have a vague memory of being told that it was a Peggy Seeger song -if Sarah reads this,she might be to confirm or deny this! Whatever the origins of the verse being queried, I've always sung it as:
The first being a brave lieutenant
A brave lieutenant and a man of war
The second being a brave sea captain
Captain of a ship that had come from afar.
As I said, makes sense to me, although it's possibly the silliest song I know........or are there sillier ones?