OP, I would reiterate that your reps should focus on objective facts (the video) and the law. In this regard..:
The council's evidence shows the following:
A 'priority' sign as defined by the Traffic Signs etc. Regs;
An associated plate stating 'Give way to oncoming vehicles' but without a specified distance over which the priority applies;
The arch of a bridge and a narrowed carriageway for the length of the arch;
An oncoming vehicle which was stationary but not within the length of the arch or narrowed carriageway;
My car entering this narrowed section.
The legal interpretation of the combination of signs is given in the Traffic Signs etc. Regs and further expanded in s4 of Chapter 3 of the Traffic Signs Manual which states that:
'Unless the limits of the priority section are obvious e.g. through the arch of a bridge etc..then the traffic sign [indicating the priorities] should include the distance over which the priority applies.'
The driver is therefore entitled to rely upon what are the obvious limits of the priority i.e. through the arch of the bridge.
It is indisputable that there were no oncoming vehicles in the priority section, indeed, the nearest vehicle appears to be at least ** metres from the end of the arch and ** m from the priority sign on that side and therefore the authority must cancel the PCN.
In order to forestall the authority from misguidedly believing that the 'Give Way..' associated plate alters the nature of the prohibition, I would refer them to s4 of the Traffic Signs Manual and the Traffic etc. Signs Regs which make it clear that a 'Give Way' restriction applies at junctions only and not along a two-way section of carriageway. Specifically:
'The Give Way sign may be used ..to give greater emphasis[to the priority restriction] and to indicate where vehicles should wait[when required to do so].