Helen was a great host, since she made it possible to get into the apartement earlier than usual in order to leave the luggage there for the day - and to keep the key longer than planned on our day of departure, so we could seize the last day without being forced to carry our suitcases along with us. (There were no other guests coming in that day - but still it was very kind of her, since the regular conditions say to leave the apartement not later than 10 a.m.
Communication with Helen was a pleasure since she answered to all mails immediately.
The apartement is located excellently: only one to two minutes walking distance to the tube (Borough station); 10 minutes from that station to Westminster! And above all a supermarket next to the main entrance - just perfect.