To plagiarise a certain expert on here ... since when did it have to make sense?
You fly a G-reg? Want to fly IFR outside the UK? You need a CAA or JAA IR.
Got an FAA IR? So get your claws on an N-reg aircraft.
Ours is switching to N-reg at the next C of A renewal date. Means we can use our FAA IRs, and also don't have to have the prop vandalised every six years (that's due at the C of A).
My next worry is that I can foresee the day when an EEC resident won't be allowed to fly an N-reg on an FAA licence.