Well bang goes my day.
I think I've discounted all the golden age Irish boys- Gandon, Pearse, Castle, Ivory, Johnston, Bindon, Roberts, etc., so I'm not sure where to go from here. Trying to remember any architects you've namechecked lately as a starting point. It is an architect, I presume?
But 18 letters long, vowels E I E I O (:D ) and 4 Rs? Shouldn't be too difficult, I'd have thought. I might be back for a clue, but not yet.