Sorry but I have to agree partly with Kit here. I know his point seems argumentative but he is right in as much in that the CAA (JAR, whatever) won't grant him (Unkle Muncle) a medical for whatever reason. The FAA will ,so great, let him fly. The point here is that to fly, generally, in the UK, the medical requirements are fixed and therefore why let people get around the rules by doing another countries medical to enable him to fly here. There is usually a very good reason why people fail medicals.
If I lost my medical here, could I then go get an FAA medical/licence and continue to fly in this country. Ask yourself this question:- Would you let me fly your family around under these circumstances. that's the standard I use.