You will find a lot of information in previous discussions:
http://www.flyertalk.com/forum/luxur...ws-london.html
http://www.flyertalk.com/forum/luxur...el-please.html

My preferred hotel in London is the Lanesborough (far ahead) and recently I tried the Connaught and was pleasantly surprised. But you will see that everyone has a strong opinion about London 'luxury' hotels here and it is not easy to make a choice.