Hmmm... just my opinion (FWIW), your leather interior looks perfect - I'd keep that colour as is, but I'd try to get some lilac / purple colour carpets to really complement the paint, then edge them in a leather to match your trim. The contract of dark carpet / light leather should look well.
We're so lucky to be in the 21st C nowadays - for the roof, go to a place that does vinyl wrapping (I think some even do vinyl spraying???), and have them experiment with a white vinyl wrap roof - won't break the bank???
If it was blue, I'd stick a Union Jack on the roof (or the entire car) in vinyl wrap.......
Cheers,
Dino
as i kept an eye on both filters .....
, how sad Krusty, 
.. Too much old material underneath the new paint, 
, it happened to our convertible years later when left in a hot storage area, most painters will only use one system, ie ICI primer, basecoat and laquer, or Glasurit system etc and only put it onto a prepared shell without the old paint underneath, this way they can be 99% sure no reaction will happen, but, this as I am sure you will know means a bare metal re-paint and all the sculpturing that goes with it on a Interceptor, otherwise this sort of thing can happen, the new coats of paint liven up all the existing coats underneath which causes sinking in the future and maybe/inevitably reactions to the finish coat like you are now suffering 
, it's so sadly annoying