Grum, if you know personally a UK FI(A) he can sign you off.
There is no need to do a flight test, or even be in the UK, as long as the FI(A) is willing to put his signature on a form stating that you are level 6.
You could do it all by email, as long as you can convince the FI(A) that you really are who you are - hence it would have to be somebody who knows you personally.