Thanks, Jim. I did wonder whether the verse was an authentic MacColl original, because there's an "extra" verse from Shoals of Herring that is almost never sung, but sounds very authentic:

You’re net-ropeman now - boy, you’re on the Nore
And you’re learning all about seafaring
Scraps of navigation, that’s your education
While you’re following the shoals of herring

I can't remember now which recording that came from, but it seems to be very rare.