It has been my belief and also my experience that where an applicant for a UK EASA compliant licence had previously held a UK FRTOL (expired or not); then they had satisfied the requirements for the RT privileges to be included in the UK EASA licence.
In the main that has been true however; where the pilot holds a National licence, if the FRTOL has an expiry date then because the FRTOL is a seperate licence it has to be renewed. Prior to the ICAO ELP requirement, the CAA would normally re- issue a pilot licence together with a matching FRTOL.
In 2006 the CAA authorised RTF Examiners to issue a level 6 ELP to all candidates who demonstrated fluent English at the RTF test to get ahead of the game. In 2008 the CAA reissued all pilot licences to incorporate ELP; it did not indicate a level or validity period and it was assumed that anyone who held a FRTOL would be at least Level 4 which is only valid for 3 years.
Whilst there is no requirement to endorse a FRTOL with ELP, the CAA made it mandatory to have at least level 4 ELP before issuing or renewing a FRTOL. Anyone who didn't have Level 4 English would not be able to pass the RTF test anyway, but the Examiner could only issue a Level 6, not a great problem as most candidates are fluent English speakers.
Things then started to get into a muddle, the CAA seemed to have no idea who had level 6 based upon either the initial RTF Test or a subsequent flight test or revalidation with an Examiner, or perhaps they just can't be bothered to trawl through the records to find out. The result is that anyone who has a FRTOL that reaches its end of validity cannot get it reissued without a new ELP. Those who were actually awarded a Level 6 are now being charged to upgrade their presumed Level 4 to a 6 even though their initial assessment may have been at Level 6. All the effort to head off the problem by early preparation seems to have been thwarted by slovenly record keeping. It seems that ELP is now much more important than correct phraseology.
The requirements for the issue of a FRTOL come from the ITU General Radio Regulations; the UK is a signatory to the ITU but EASA is not.