Thank you for the information, I didn't know that Fairmont & Raffles were owned by the same group. I have never stayed at a Fairmont property, is it really that bad? (I read some comments about the Plaza in NYC managed by Fairmont and it seems indeed quite disappointing.) Regarding Raffles, the only hotel I know is the one in Singapore. I stayed there twice and it was fantastic both times.
The Lanesborough is just above the 'Hyde Park Corner' underground station. Clearly the location is unbeatable.
Regarding service, reception staff is smiling, professionnal, and very efficient. We were shown our room within less than 5 minutes after having entered the lobby (which -by the way- is quite different from standard 5* hotels lobbies, it feels more like a private club).
Our butler was waiting for us, he showed us the air-con/lighting system (a discreete remote control in the bedside table which use is very simple -you don't spend hours looking for the right switch like in many other hotels

). He also offered us a welcome tea. Internet access is free of charge, and there are plenty of complimentary services.
The bathroom is well appointed even if a bit tiny (only one vanity, but separate bathtub and shower). All products were presented in nice big bottles.
I feared that the butler would erupt in the room at any time, but it didn't happen. All furniture, carpets, equipments were in mint condition.
Regarding food, we requested room service on the first evening. Delivery was incredibly quick (probably no more than 5-6 minutes) for two Caesar salads. The breakfast is served in Apsleys. Decoration is nice, we were very few people in the restaurant, nothing special to say about it. The afternoon tea is fantastic, even if there is too much food for me...
Only two negative points: security staff on our floor was everywhere (we wondered if some VIP was staying there), and doormen were not enough (one car only and they were all busy).
My english is still terrible, sorry for that. If you wan any specific information just tell me and I will try to complete my story.