What is the maximum age for renting a car in Ireland
and the UK
It depends on the company. I "think" most are in the 70-75 range.
And be advised that a second driver really drives up the cost, doesn't matter if you're married etc. Ask ahead. Otherwise driving in Ireland was very pleasant and you couldn't ask for a more polite and helpful people. If I ever get lost or have my car break down in awful weather I'm praying it happens in Ireland.