OK, but it doesn't really matter where we live.
I can't understand why someone who has held a PPL for over 20 years and also has been living in the UK for that time is assessed at level 5. You must attend an approved language school to be assessed at level 5. So that must have happened. The CFI/HOT of his flying club could issue the short letter confirming his continued use of his RT use. Holding a UK licence allows that a local FRTOL examiner or a Flight Examiner may assess him/her to level 6 with a simple form submission, so why not.