Jeremy,
"Perhaps someone can provide the definitive answer, but I don't think its worth arguing about, I suspect its one of these 'depends on period or works that did the job'"
I suspect you're right. Certainly the Bachmann representation doesn't tie in with this
http://georgestrainpics.fotopic.net/p64136891.html
On my earlier point about the pipe+rod on the lower rhs firebox, I notice the holes for these are present in the cab front but not in the footplate. By the way, the rod does not go as far to the front as on A1s and some A2s lost the pipe in later life whatever it was for (see picture of 60528 above).
It has been suggested that the unsightly seam above the sandbox fillers is to allow for different boilers. Is it not more likely that the cab/firebox/upper boiler were carried over from the A1 moulding (albeit with different mudhole patterns) and the seam represents the join up to the different footplate? There is also a seam in the footplate just in front of the firebox and the holes in the cab mentioned above will be a hangover from the A1.
By the way, shouldn't the tender front be higher on early-liveried A2s?
Alan