I'm bumping this up - Paul (chuggy) had a look at it when we met on Monday, and is positive it isn't Italian.
It looks as thought the glass was dipped in a sort of coating, and then blown, so the coating spread out and broke up. There is coating on the base as well as the main "bulb" of the jug, and a bit on the neck, the coating is finely granulated, but smooth to the touch.
It is a delicate little thing. And I dearly want to know where it is from, and when!!