I'm still having some difficulty in getting good photographs of the 1930 proof coin (due to limitations of the camera, lights, and to a degree my, lack of, skill). I've had a good close look at the coin. Both the obverse and reverse show clear mirror like reflections of nearby objects. This immediately suggests the coin is indeed a proof. I tried to photograph a pencil placed by the coin and it's reflection shown on the coin, but camera lens depth of field limitation (f8) didn't allow clear photographs of the coin, pencil and it's reflection. Thanks to Coppers link, I have an idea of valuation (something in excess of 300 pounds it would seem). The coin was purchased through Farthing Specialist about 20 years ago. FS, as far as I know, were quite reputable. So if FS says the coin was a proof (as it seems to be), then the 1930 coin is a proof.