"Overlooking it all is the signal cabin, the last one standing belonging to the old railway line...."
Nope - Ballynoe (just about), Killough and Tullymurry BCDR cabins still remain. The signal on the platform is an ex-NCC somersault, brought to the station by the long-time owner Mr. James Black who was an NCC employee, originally from Castledawson I think. I visited him and and his wife at Saintfield on many occasions.