I came back from london on Tuesday and here is my opinion on the places I finally went to:
Greens: good atmosphere, quite expensive but good quality of food and EXCELENT service
Savoir fare: Absolutly fantastic!! great food at great price and if you get to sit by the window, fun to see the street...
vilandry was closed when we tried
we had luch at the restaurant on top of Peter Jones, good views of london, but the food and service, quite crappy...
thank you all for your help!! We had great fun!!!

Basic rule: Food depends on the chef/cook and the crew. No restaurant has the same crew working seven nights a week. Follow the cab drivers!

that's true!! but our waiter was EXCELLENT and the rest of the "crew" was good as well. Maybe we were lucky, but that is all I can say about the restaurant (about greens)