I don't think option 1 applies Steve (after considering all the comments flying about on MogTalk).
Date of first reg as far as I can tell is when it was first registered in the UK for the road. Doesn't matter whether it was previously on a 'cherished' plate.
If you look up S341 EGJ it wasn't first registered in 2009, but in '98. Some time later it was on a private or cherished plate, for a number of years (K600MOG, now on a Roadster) until the time I bought it last year. It was returned to an age related plate (OK the same reg as when first registered), but on the DVLA database the date of first registration is when first registered in this country. Mind you, DVLA do not always get things right (e.g. my TVR Tamin

)
So, is it a foreign reg car, re-imported? To manage 9k miles in the space of a week or so would be some going!
Cheers,