From memory:

Come all you warlike seamen that to the seas belong,
I'll tell you of a fight my boys, on board the Nottingham.
It's of an Irish captain, his name was Somerville,
With courage bold he did control, he played his part full well.

Now was there a Captain Somerville, Summerville, Sunny Bill or whatever that was in charge of the HMS Nottingham?

Was the captain's name right, but the ship's name wrong- or vice versa?

Or was the whole thing made up by a penny-a-line balladeer?

And why does the ship's name and home port change half way through?