We have spent a week at Sally's place, which was very convenient for us, close to our work, we just need to walk 5 mins in the beautiful Battersea Park. I could easily find buses just around the corner wherever I wanted to go in the city. We didn't get to meet with Mathias and Sally as they were abroad but the communication was always fast and easy. The house was clean and the beds were really comfortable, the only thing that could be difficult is the stairs up to the third floor if you are carrying a big luggage, but this is life and it has nothing to do with the hospitality of Sally and Mathias, overall I highly recommend the place, hopefully we'll be back!