I thought you were innocent until proven guilty. It seems to me that if the conviction was unsound, guilt has been shown to not have been proven. That means he is innocent. Whether he did it or not is another thing.
Well, I seem to remember reading something in the Press many, many years ago soon after Mr Davis was released after the campaign that claimed he was innocent of the crime that he was put in prison for, that some months after this, he was arrested on another hold up job. Not sure if I read this correct, or if it was just alleged. The Geezer was a career criminal, so it was alleged.