Mad Jock is right.
It is in the IR section E of Lasors for renewal requirements;
"Where less than 7 years have elapsed since the IR(A) expired but 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 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."