See CAP 804 Part I Section 3.
Other Member States have been more generous than the CAA with respect to IR recognition. The CAA changed from:
LASORS2008:
However, where IR privileges have been exercised in another category of aircraft (i.e. UK/JAR IR(H)) or under the privileges of an ICAO licence (Aeroplanes and Helicopters) or under a UK military IR qualification (fixed-wing or rotary), the renewal requirements will be based on the expiry date of that IR.
to LASORS2010:
Where less than 7 years have elapsed since the IR(A) expired but IR privileges have been exercised since in another category of aircraft (i.e. UK/JAR IR(H)) or under the privileges of an ICAO licence (Aeroplanes and Helicopters) or under a military IR qualification (fixed-wing or rotary), the renewal requirements for the IR(A) will be based on the expiry of that other IR.
If more than 7 years have elapsed since the IR(A) expired, no credit will be given for any other IR rating or qualification, and the terms set out below for more than 7 years since expiry shall apply.
without any warning or justification. The IAA are aware of this absurd situation and are, I understand, quite happy for pilots with UK-issued JAR-FCL licences to change their State of Issue to the Republic of Ireland, in order to avoid the absurd nonsense of retaking exams after 7 years of JAR-FCL IR expiry even though IR privileges are being exercised on other ICAO licences.