There was a 'general reluctance' to sign in the early years at Mdina - part of the Harris philosophy. Michael Harris' signature is found on some but by no means all of the well executed and larger items. Many items for the American market were simply engraved Mdina (with a diamond point). So the majority carried no marking at all.
So far that is pretty much all that has surfaced as far as I know from 1972 or earlier, apart from a couple of items that also include personal inscriptions (one of which I have here).
I am suspicious of the signature on this goblet, there is something vaguely familiar about the goblet, perhaps it was sold on ebay in recent months. The signature does not look 'right' to me, hard to say exactly why but it's position is odd for one thing. It could read Ettore or for that matter Eric Dobson, if it read Ettore that would really make me suspicious....
John