Whether it's surprising to have the charge or not jake, the judge must have left s18 to the jury and the jury found her guilty of s18. No doubt the whole of the evidence proved it. Just the evidence that the woman wielded a bat so hard and/or so often that the victim was in a coma with a fractured skull and near death tends to suggest that she intended, meant, gbh when she hit him (however she came by the bat, she knew what sort of thing it was and how to use it). That evidence alone on the papers ought to justify the charge of s18. Of course, to take an extreme example, if someone just punches a man once and he falls back and breaks his eggshell skull on the kerb that's different, and a s20 ! If it were one blow with the bat which,very unluckily, broke his skull she might have a run on self-defence ( seems reasonable in the agony of the moment, therefore is taken to be reasonable), but anyway should really only go down on as s20, because it would be very difficult to prove intent. Prosecutors might then, perhaps, only charge the s20, given that and would certainly seriously consider an offered plea of guilty to that, as adequate if they had charged s18.