So does the holder of a JAA FCL licence issued in another state require a UK FRTOL to operate in UK registered aircraft?
No, their JAA licence is validated in the UK by ORS 4 No 747. There are occasionally cases where a RT licence may have been issued based upon another language however that is largely covered now by the requirement for English Language to operate Internationally.
he trys to get his JAR PPL in Germany and asked me to find out about possibilities to get the RTO in Britain, as he frequently has to do some busines there..
If he gets a JAA PPL in Germany he will not need a separate UK FRTOL!