Upvote:1
As far as I can tell, a foreign license is good enough.
The Irish RSA website says:
the person who’s with you must hold a full driving licence for the category of vehicle you are driving for a continuous period of 2 years.
It also states that a permit holder can't be an accompanying driver.
The citizenshipinformation.ie site says:
Car drivers with a learner permit must be accompanied at all times by, and be under the supervision of, someone with a current driving licence for a car. Also, the person accompanying you must have had the driving licence for at least 2 years.
Note that although these are official sources, they are not the law. I think the Road Traffic Act (1961) is the authoritative source, but I didn't find mention of an accompanying driver there.