Thanks Sam, I've just found what could be the answer - and I (we) might not need an FAA BFR.
Part 61.19(c)(2) says:
The holder of a pilot certificate issued on the basis of a foreign pilot license may exercise the privileges of that certificate only while that person's foreign pilot license is effective.
Last edited by Kemble Pitts; 16th June 2019 at 19:34.