Hi Jonathan, huge fan of your photos, useful and inspiring
I helped out with the research for this model, and given I wasn't even 5 years old when they stopped regularly running on the Enterprise most of the info was gleaned from research both online and talking to people
Past 1984 they were not common on the Enterprise at all - they were not as reliable then, plus I'm not sure if non-CAWS fitted locos were allowed south of Malahide then (which was the furthest that CAWS reached on the Belfast line then, was there special permission needed, loco inspector in the cab etc). I'm sure lack of maintenance etc ended push-pull operation, given the 111's didnt use it
Coach lamp irons - I know BR MK2's had two, one high, one low, IR ones were both lower down, as long as there was a lamp iron there it was sufficient, later the two rule came into place.
Hunslets only had one lamp iron, be it for a tail lamp, the GNRI white square to mark the rear of the train or occasionally a tour headboard. It was well out of gauge too
The great irony of it all is that the Hunslets shared plenty of parts with the BR Class 20 and Portuguese CP 1400 locos, both of which are renowned for reliability and yet their NIR cousins didnt even last 15 years on the frontline