This was first class in every regard. Pierre communicated with me early on in detail as I made my reservation several months in advance.
When we arrived, we walked straight to the flat using his instructions and Christine met us and gave us a very nice walkthrough of the flat and amenities.
We enjoyed the wine and other food items left for us to use during the stay - a very nice touch.
On the few occasions we needed questions answered or anything else, Pierre seemed to be "on call" all the time! It was never more than 10 min before we got a very friendly and helpful response - extremely comforting.
In short, I wouldn't hesitate to recommend this flat (or Pierre and Christine) to anyone. The experience makes you really enjoy London that much more!