Thanks for your help guys.
Had a chat with the Nice people at Ontrack and they put me straight. It's as Bose-x says.
FCL.905.CRI (b), the bit with 15 PIC in the previous 12 months does not apply for the addition of ME CRI, it does apply if you, say, wanted to instruct in a Cessna caravan and hadn't had a CRI test in one.
Sixgee