OK, I give in. I still can't achieve 103 cells. 98 I can do, or 109. It's the interpretation of the third word of the instruction which I think is the problem. Let's call it "X'ed". The first cell in the grid is not X'ed IMHO, but outside, so maybe I should exclude it? Since we're into the 140s now I don't think I'm giving too much away by setting out the cells to which the instruction applies in column order, hoping that some kind soul will put me right. In order then: 7, 5, 12, 10, 9, 8, 7, 8, 9, 10, 12, 5, 7 (ie. 109). Where are the extra 6? (No doubt it will come to me within moments of posting, but I'm not holding my breath: it's been several hours already.)