In my mind, you might have had a GSR competing with a GNR combined with the DSER. Eventually theyd still end up combining into a CIE of sorts. Though the railway map would be impossible to predict, considering the economic position, structure, policy ect. of such a country would be much different. One thing is for sure, I’d imagine there would be a railway line running up the North West
Imagine gsr grey donegal tanks….GNR 461 ect.