Michael, stevejobsfan123, many thanks.
Problem solved. There was no menu optin to turn off iTunes Match or even to turn off iTunes Store. There was only an option to turn them on no matter what I did. So, I turned them on and followed my nose until I got an option to turn iTunes Match off (in the main window not, in the Menu).
Now I'm back to an old problem. iTunes always tries to connect to the Apple site (ax.init.itunes.apple.com) even though the Store and everything else I can think of is disabled. I've disabled iTunes, Ping and Sharing in Parental controls but it still wants to phone home. So, I've resorted to blocking it in LittleSnitch.