Amazing
Just after I'd given up I got a response from the CAA. In case its helpful to someone:
"I can confirm that if you obtain a JAR CPL(A)/IR with ATPL theory, under current arrangements you would only be required to pass the JAR Principles of Flight (Helicopters) examination at ATPL(H) level in order to obtain a JAR CPL(H). However, you should note that these terms are a temporary arrangement pending the availability of JAR bridging examinations which are expected to be available by the end of the year".
Thanks for your replies
