I wasn't aware you had to have an FAA license to fly an N reg, I have mates who fly N reg aircraft on UK ppl's
I understand that it is legal to do so within the British Isles. It is not legal for a UK PPL holder to take an N registered aircraft to the Channel Islands.
If Flying Lawyer is still monitoring this thread, could he please provide the definitive answer. I don't spend much of my spare time studying air law.