My family, including our 5-year-old daughter, stayed here for a week. We had a great time. The flat is very cute - in the lower level of a pretty 19th century London whitewashed house. We had a heatwave when we were staying here, which made the place pretty hot, but not unbearable. It's a very quiet area, incredibly convenient to get to all the London attractions. The Pimlico underground station is at the end of the street, which was amazing.
The flat is only a 5 minute walk from the river, and you can take a walk over the river and catch the ferry up the river to the London Eye if you want, rather than taking the Tube.
We were greeted by Simon, the owner, at the door - he went to great effort to get us in on time even though he and his wife had trouble scheduling their cleaner for the flat. We were very grateful as we had flown a long way!
The only negative we had was an ant problem, but that was probably just due to the heatwave. Absolutely perfect place for a family holiday.