I can only recommend Valentina's loft and confirm what other reviewers have already pointed out about the accommodation. Moreover, I was very impressed by Valentina's forthcoming gesture to buy us some food for dinner as we arrived very late due to a plane delay.
The loft is situated in a nice and quiet green neighbourhood with a playground nearby. There is a supermarket and some pubs at the underground station. It is very central - the London Eye is e.g. 4 stations away. It sounds like a cliché but I am sure we would only stay at her place the next time we come to London.