From what I remember whilst it may be one leg you may find more information on the ticket itself. You may have one that says for example Liverpool street to Norwich then another part with the reservation for seat. It's the stations this part states which is crucial. They normally take a couple of weeks however any information you include with the appeal is all they take, so they won't say its insufficient more likely they will deny it. Within the letter they will state the reason why and also give you further details of the next step normally pay up or write to the ombudsman. However if you feel your information is insufficient write again asking for it to be taken into consideration with the rest of your information. As bazza rightly pointed out. Gate staff said was ok is I'm sure a common excuse however in your defence a member of staff for the operating company agreed your travel so therefore that should be good enough. Worth pointing out your asking of the staff would of been captured on CCTV as Liverpool streets gates are fully covered by CCTV. Which providing your account is correct they would be able to see. As would greater Anglia if your appeal is unsuccessful.

You ever tried to get gate staff to leave their post. It doesn't happen. Despite the valid ticket argument to which we already know that he didn't technically have a valid ticket sympathetically it needs to be judged in his favour. And on advance tickets you often find the timed part is for a particular section of the journey ie ipswich to london the Ipswich to Colchester part is timed the rest isn't and you are free to break your journey at this point. ( this is on GA terms ) Also you can take any train on the untimed part. So op should look at tickets and see if he was on a timed section of his ticket or not. If not the fine is invalid unless he was fined within the timed section. Would be helpful is OP clarifies this also.

I'd say your chance of getting this revoked is pretty high. From the times I have had to appeal ive always found the IRCAS to be fair. Firstly did you note description of barrier staff in your appeal or name ? and did you make it clear to the issuer of the fine of your reasons. If so on the latter thats a complete jobs worth tbh. But I see no reason that they shouldn't revoke. If they don't then simply write another letter to them and to Greater Anglia, advising you will not be paying, your reasons and details of the emergency and ask that this letter be held on file if they ever wish to pursue recovery in court £61.40 theres no chance !