But the FRTOL is a UK National Licence not a European Licence. There is no such thing as a JAA FRTOL!
The UK ANO states that a FRTOL shall have a validity of 10 years, for a stand alone FRTOL that is what it has.
When issued in conjunction with a Pilot Licence the two licence validities are aligned to ensure that both licences remain valid for the same period.