I almost give up in despair! There should have been absolutely no political discussion surrounding the appeal, and the matter of a petition should not have been raised in the Court of Appeal (how was that relevant?).
The guy held a weapon unlawfully - for a considerable period of time - and he held a considerable amount of ammunition unlawfully - kept in an insecure manner at a civilian address. Whether he was trained to handle weapons or not is irrelevant - except that he knew of the dangers posed by such weapons, and he would have been aware of the seriousness of the offence under the Firearms Act. Yes, there are factors in mitigation (reflected in his original sentence and the degree of leniency given by the original JA) but claimiong 'cos he's a hero, he shouldn't be put in prison' is complete and utter rubbish. I would look forward to the same degree of leniency if I faced similar charges*
* except I declared the items under OP PLUNDER and took the necessary administrative actions on my return. But then I'm not special, and don't suffer from that hitherto undiagnosed condition of 'poor admin'. And I've been busy, too, even if I haven't claimed that my ears went pop!
This case (and the hysterical medja and public reaction) has seriously undermined the Service Justice process. It will be interesting to consider how he will appeal his guilty plea.