I know the answer has appeared numerous times - but the promised response from the FAA has just arrived and says...
"
I talked to <<name edited out>> in OKC to get the answer to your question.
The FAA certificated CFI may give a BFR to an FAA certificated pilot
in a non U.S. registered aircraft in another country. Obviously, the
pilot in command would have to meet the requirements to fly in that
country (pilot certificate, medical, currency requirements of that
country, etc..). Hope this helps. Let me know if you need more info."
"OKC" is the abbreviation for Oklahoma City - the Head Office of the FAA.
Think we've done enough with this one!!