It is amazing how, sometimes, a little research brings forth an unexpected answer
The UK position is set out at http://www.nationalprivatepilotslicence ... ew/FAQ.htm
Q What do I need to do to fly microlights on my light aircraft (SEP) licence?
A You may fly microlights without any further training or testing within the privileges of your CAA or JAA issued PPL (A) if you have a current SEP rating. You are advised to take conversion training with an instructor. You cannot use microlight flying hours towards the maintenance of the SEP rating. If your SEP rating lapses and you wish to continue to fly microlights you should apply for a NPPL with a microlight rating attached. The requirements are given in the cross credit document on this site
Being careful to take on board HUM's very correct caution about belief in website gossip I believe this is still the case in Ireland
Nothing has been done (yet) to diminish the Irish PPL
Possibly because it would be invidious to take from local PPL's freedoms automatically enjoyed by any visiting PPL