I had the pleasure of spending close to a fortnight in this fantastic apartment that's smack-bang on Clapham Common, with the wonderful Windmill Pub directly opposite, the less salubrious (but still welcoming) Rookery a couple of minutes away, and both Clapham Common and Clapham South tube stations within 10 minutes' walk.
The owners were incredibly helpful and responsive but also discreet, so I felt relaxed and at home in the apartment at all times - and the quirky, boho-esque decor made it feel like an inviting place to just hang out and watch the world go by. The only thing to note is that the apartment is up four flights of stairs, so if you have mobility issues then you may want to exercise some caution here.
I'd love to stay here again when I'm next back in London - and I'd heartily recommend it if you're planning a stay in Clapham.