Hi Things have already changed, when you look in JAR FCL 2 see the following;
JAR FCL 2.285 This use to state that CPL(H) & IR(H) = an ATPL(H) theory credit, you will see in the new version of JAR FCL 2 this is not the case. (Version 4 issued August 2006)
JAR FCL 2.050 and appendix 4 to 2.050 gives information of crediting on theoretical knowledge.
JAR FCL 2.495 state the validity periods for theory exams, 2.495(b) applies to CPL and ATPL VFR and 2.495(C) applies to ATPL IR.
LASORS J1.7 makes reference to JAR FCL 2.495 and states if you have not been issued with your CPL(H) and IR(H) within 36 months after passing your ATPL(H) theory you will have to resit all the ATPL(H) exams.
JAR FCL 2.495 as far as I can see does not state that you have to re-sit all the ATPL theory (14 exams) (if no IR was obtained in 3 years) in order to gain an ATPL(H) IR.