Just recently (April 2013) we stayed at the Main House in the Notting Hill district of London (on the quiet corner of Colville & Lonsdale Roads) for 13 nights. This is a small B&B (5 rooms I think) located in your typical London row house, probably dating to before the turn of the last century. Our room, essentially the entire second floor, was quite huge - one could almost play football in it - and very nicely decorated with antiques and original oil paintings. A concern for many travelers, the private bathroom was also quite large. Caroline Main, the innkeeper, and Chiara, her able assistant, were both the very hearts & souls of good cheer, and were very helpful in every possible way too, with restaurant & shop recommendations, transport info, calling a reliable car service, etc, etc. Tea or coffee was served on a silver service in the room each morning. There is a common fridge where one can store one's own personal stash of drinks & edibles. All in all it was quite a good show, and very reasonably priced. When we are again in London we will most certainly try to book a room here. It's a small place so booking well ahead is essential.
The inn is located at about a 10 minute walk from either the Notting Hill Gate or Ladbroke Grove tube stations. The red double decker London Transport buses - several routes with frequent service to many different parts of the metropolis - stop about a block away. The inn is also a convenient one block walk to the Portobello Rd antique shops and weekend flea market, and also to many, many shops, cafes & restaurants. A discount of 10% at several nearby shops, restaurants & cafes is provided to guests at the Main House.
One piece of advice: this is very much like staying in someone's home. Those travelers used to the standardized amenities and the obsequious concierges & bellhops of the Hiltons, Hyatts & Kempinskis, this will probably not be your cup of tea.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.