Additionally, there are whole airlines happily operating on foreign registers in the UK.
Ryanair, for example, merrily claims that its main base is Dublin. Eire is JAA so despite it's slightly flag-of-convenience flavour it is perfenctly entitled to operate in the UK.
Air Atlanta - Icelandic. You'll see lots of supposedly British Airlines (like VAA) using Air Atlanta aircraft to operate in the UK.
Therefore, I find this whole N-reg thing barmy - the AOC costs from Ryanair alone would knock any financial gain out of the private stuff for six...
It's all rather strange - why not delve into the TF and EI register game to draw precedent?