If you want expensive but not French in London you might check out the Ivy. As to Paris, heavens, L'Arpege is up there but so are all of the 3*s. For lunch my experience was that L'Arpege was more than Gagnaire or Taillivant unless you get the special tasting menu at Gagnaire. That with some drinks goes about 300-500 Euros per person. On the other hand, I had the lunch special at Gagnaire (not the like 9 course tasting menu) and it was a real deal for what you got. I think it was about 50 Euros for lunch.