Hdc prison refusal, going to appeal, please help.?

My partner is in prison and has been denied hdc as he has been recalled on a previous licence, the thing is he is going to appeal it as he was only recalled on suspicion of commiting another offence, when it went to court it was thrown out as insuficant evidence and was never sentenced for it, what are the chances of the decision being changed to grant hdc? Many thanx