Possibly just based on set availability?
On the regional routes what demand there is on 1st class is mostly on trains that arrive in Dublin before 11am or depart from Dublin after 4pm.
Rather it sending it back on a long route where it would be out of place to operate a late service from Dublin, maybe it's handier to have it do a few runs to Kildare.
Presumably, if there's not officially 1st class service on it, anyone can sit in the 1st class carriages on the run.
|