It's a parody of an older song about the mining in that area, and some of the original words carried over. Only a fragment of the older song was preserved but presumably everybody around Edinburgh or East Lothian knew it at the time.

The military situation has been re-evaluated recently and it seems Cope didn't actually make any serious mistakes. He just in a hopeless strategic position to begin with. There are no good defensive positions there (as it happens I was out near there on a bus a couple of hours ago) - it's just an undulating gentle slope up from the shore. No towering heights to place cannon.

The tune has been said to be a variant of "Katherine Ogie", but none of the words from any form of that song got into Skirving's.