Hi Greg,
As summarised in my previous post above and here, my girlfriend went through exactly the same process. She even had the opportunity to talk to TFL, who were no help (i.e. they are right and you are wrong). I guess Bernie_the_Bolt got lucky to have success at informal appeal stage.
She received a formal rejection, which seems to be a standard procedure. In fact, I recall she had to request this, since an Enforcement Notice was issued before any rejection to her informal appeal. We then put forward an appeal to PATAS. Main point we focused on was the inadequate signage, as the PCN states that applicable reason must be used. We did also add the original appeal and pointed out that no requested evidence was sent out (almost all the items Bernie specified above in his original post). Basically follow instructions on appeal form.
There was an acknowledgement letter, stating appeal was received and the date when it will be reviewed by an adjudicator. True enough we got a response, the adjudicator allowed the appeal on grounds that there was no breach of the bus lane order or regulation. Reason given was that the Local Authority did not send in any evidence and as lamma explains, all evidence has to be sent.
Personally, I would encourage you to persist with the appeal, although there are no guaranties. If you have not paid already and missed the deadline for 50% discount, I don't see why you would not go ahead. There may have been a few cases of success, which is very inconsistent and I would point this out to the adjudicator, (i.e. how one person can be allowed an appeal and others not). I don't know if the Local Authority find it too much work to respond or simply feel that if they lose they must respect the rest of appeals or fix the bus lane if it is wrong. I am no expert on this, but wish you luck if you go ahead.
Regards,
RV