We would definitively recommend Mark's place. First, the location is perfect, a five minute walk to the Sloane Square tube station and in the heart of Chelsea. Second, the flat is clean, spacious, and thoughtfully put together. Third, check-in and check-out was seamless (key in a lockbox). Fourth, Mark is a great host. We asked him a lot of questions and his answers were always timely and informative. He had many good suggestions. This really helped us plan out our trip.