22 I do not accept the submission that this was a case in which there was no room for mistake. The appellant's evidence as to precisely what harm he apprehended and how he apprehended that harm might arise, was extremely unclear. On any objective view, the threat which he faced at the time at which he assaulted the complainant was not a significant one. There had been no violence offered to him on the earlier occasions on which disturbances had taken place outside or in the vicinity of the shop. On this occasion, while there were numerous other persons about, the only person offering any violence was the complainant, and that violence was a punch. There was some evidence, which the jury might well have accepted, suggesting that the appellant's conduct went well beyond that required to respond to a threat of that nature: the medical evidence suggested that he inflicted significant injury on the complainant; the evidence of Mr Thompson, the complainant's friend, suggested that the appellant's retaliation or defence involved not only punching the complainant but also kneeing him in the face; while on the complainant's account he was punched when he personally had made no threat and offered no violence to the appellant. In those circumstances, it seems to me that it was prudent for her Honour to leave to the jury the possibility that in the state of "panic" which he said had been engendered by the banging on the glass of his shop, the appellant had perceived a greater threat from the complainant than had actually been offered to him.