have a look at Gary Rhode's one in the "Gerkin" building - the food is good (you can find much better in London of course) but the view is amazing and not too far from Big Ben. There is also a champagne bar in the building - again with the views over the city.
If you are after great food first of all - then i would try something like Petrus, or Gordon Ramsay on Hospital Rd - or Gordon Ramsay in Claridges...
What kind of age group and about how many involved? Any culinary hates? Any £££ considerations? Do you want somewhere which will be jumping at midnight, or do you want to be near Big Ben/ Trafalgar Sq. by then?
Maybe Langan's in Stratton St. or somewhere good in Chinatown?
re: Robin Joy
Oh yes in fact... here some more details:
We are a couple,the kind of food doesn't matter but it has to be very good. The budget is not a problem but the place has to be worth the money I spend...
For midnight we would like to go to Big Ben, so the nearest the better!
Thanks a lot for the suggestions!!