Irish: €15 for a three-year passport (under threes only)
Irish: €25 for a five-year passport (ages 3 to 17)

British: child under 16 (valid for five years) £36.50 / €57.00

Well, that’s an easy decision then.

(For adults it’s a bit more competitive, €75 Irish to €88 British, but not a live issue for us right now.)