I had a really wonderful stay at Martin and Michele's. Their house is beautiful, and once inside it felt more like I was staying in some countryside cottage than London! They were very gracious hosts. Michele was only there on the first night as she then went away, but I received such a warm welcome from her. Martin was great to stay with, very friendly and had some fantastic recommendations of things to do - and not just the usual London touristy things, but he took into account my interest in swing dancing and was able to tell me about various events that I otherwise might have missed. As I was working Mon-Fri I didn't really spend any time there in the day during the week, but it was nice to be able to come home to a such a homely house after a long day. The area was handy too. It is Zone 2, and the great transport links mean that you can get into central London very quickly. There are also some lovely places to visit within walking distance - I'd highly recommend the Columbia Rd flower market which was only about 10minutes walk.
Overall I would highly recommend both the house and Martin and Michele as hosts.