You could well be right, Graeme. Not knowing whether the questioner had done a Google search, I just put "Rockness Island" into the slot and it came up with several references to such an island near Perth. I have to confess I didn't double-check it elsewhere. Now you've made me look at my state-of-the-art atlas, I find no such place in the index! My apologies to you, Deathwatcher, and let's hope someone comes up with a more appropriate answer. Are you sure of the spelling yourself?