Shri broke into Ryan's house one evening. Ryan suffered depression and anxiety as a result of being robbed in an unlit carpark a few weeks earlier. Ryan came downstairs and saw Shri rummaging through drawers, holding what looked like a knife in his hand. Ryan grabbed a knife and stabbed Shri causing a deep cut to his arm. Shri managed to escape. In fact, Shri was holding a torch.

Over the next few days Ryan sank into a serious depression and suffered panic attacks. During one of these episodes, Ryan took a few pills that had been prescribed by his doctor to calm his nerves, even though the doctor advised him to take only one tablet a day. Ryan began to feel dizzy and suddenly heard noises coming from the street. He thought he heard voices shouting his name and laughing. Ryan grabbed a hammer and rushed outside and spotted a boy who looked like Shri. Enraged that he was back on his street, Ryan ran over to the boy and hit him with the hammer repeatedly over the head. In fact, the boy was Curtis who had been playing a game of 'cops and robbers' with his friends. Curtis died in the attack.

Advise Ryan on any DEFENCES he can plead to charges of s18 Offences Against the Person Act 1861 in respect of injuries to Shri and Curtis's murder.

Detailed answer on what defences he can plead to.