A contradiction in terms I know, but in this desolate tourist area there is a (comparative) bargain to be had.
Within the Mandarin Oriental Hotel, next to the much feted Foliage (see lots elsewhere), is the relatively 'umble Park Restaurant which still is a good looking room with big glass windows towards Hyde Park. Monday to Friday at lunchtime they offer lunch for just £19 for three courses inc service, tax etc PLUS AS MUCH WINE AS YOU CAN DRINK. This is not just a two choice set lunch but any three courses from the extensive (50 odd listings) menu. The place is not trendy but just good old fashioned, comfortable, understated quality. All the food is fairly classically cooked with top ingredients and very well presented without being chi-chi. There are many favourites plus plenty of Asian options befitting the hotel - the dim sun starter plate is a fine piece of cooking. I am not sure of the logistics behind the scenes but the kitchen seems to be very competent and it is only in a hotel such as this that you would trust such a diverse menu.
Service is charming and balances professionalism with friendliness, I haven't noticed how they fare on the napkin test but I'd wager they do well.
There are two choices of white and two of red - all four are perfectly good with your glass being replenished as frequently as you desire for as long as you desire.
For the hotel the economics can't add up - already possibly the finest grilled sole in London has been taken off the lunchtime menu, but for the punter it is tremendous value. Where else can four people have a fine, large, long relaxing lunch with limitless wine, decent food and be well looked after for less than £80?
There is even the wonderful bar to retire to afterwards where I can vouch that they serve a mean martini throughout the afternoon