Very nice and friendly guest house. Fresh and cosy rooms with everything you need, including free WiFi. You get well taken care of here. The breakfast is ok, abouth average for british standards. The communication couldn't get much better, since Clapham Junction station is around the corner and you'll be in central London in no time.
The only thing I can critisize is the heating. Even at maximum setting, the radiators switched off from time to time and then the room got quite cold.
All in all I can really recommend the Lavender Guest House. It's good value for the money and I will definately return.