GSV is 5-years old, so possibly of limited help.
The signage does not appear to be of the required standard in GSV e.g. there's a sign at the junction of Edision and Grenfell but this is orientated for traffic passing along Grenfell, where there aren't any footway parking areas, and not traffic turning into Edison. I suspect they put it there because it's on the same column as the street sign and they expect drivers to join up the dots!
But the fundamental problem is that parking on the footway is prohibited by statute and in default i.e. it does not require signs, therefore on the face of it she was in contravention.
The potential existence of a white knight arises because the council had to disapply the statute for the boxed areas and often when this is done they simply allow parking along the whole street and think that adding markings can be done later as a purely administrative arrangement. But it cannot, they must either specify exactly where the boxes are to go and their size or, at a questionable push, delegate authority to the council's Director of Highways or equivalent in consultation with one or more specified councillors to add this detail.
Until they produce the council resolution you won't know whether the location allows parking, albeit that they've c****d-up the markings or whether it's only boxed areas in which parking is allowed.
