John. the woolwiches instead of the 500s would make sense as you said.The woolwich moguls could work on the Mullingar Athlone Dublin route which the larger engines probably couldnt ,because of their axeload.still wouldnt they have enough money to build the 500s if they scrapped the 400s?I think if CIE had named their expresses it would have made them more profitable and in larger demand.They could have learned alot from the GNR if they were not to busy closing some great lines.