I am surprised but if Shona says that I see no reason to doubt her. It would be interesting to know what Shona said or asked in her letters.
Jeremy's letters are censored. That may be why he was unable to answer if it was specifically surrounding the case.
The vast majority of folk who write to him just write about everyday happenings....it's easy on the brain to reply to these.
Put yourself in his shoes. He reading through copious amounts of paperwork....labelling it, sorting it etc...his mind must be numb by the evening when he comes to reply to friends and supporters. Therefore, imagine if he then read Shona's...if, and that's a big IF, it asked questions and questions just about the case...and he sensed from her letter she thought him guilty....he most probably thought his precious time could be better spent replying to friends than to one who sees his conviction as sound.
Well, I think I would do just that if I were him. This is a very, very stressful time for him. He is under so much pressure. If you do not believe in his innocenec, he may not have the time at the moment to try and convince you otherwise, afterall, he has, supposedly, enough people out here supporting him already.
Rather than I judge Jeremy, it's easier for me if I try and put myself in his shoes....at all times.