Cecilia is one of the most responsive and helpful hosts I've ever encountered. We had a terrible time with our connection to London due to systemwide train problems and she was patient and helpful with accommodating our late arrival; even helped us with our luggage! She also helped us out when we accidentally turned off the power to the boiler and couldn't figure out how to turn it back on.
The flat is tiny, as is typical for London. The main room holds the bed and a hotel-type unit with drawers and a small kneehole area and not much else. Kitchen is narrow galley-style, but has almost everything you need.
Our main quibble is that (for those of us in the US, anyway) the bed is not a king--it's a queen at best. (We have a king-sized bed at home so know exactly how big it's supposed to be.) It's also VERY soft --which some people like, but some don't. Usually Airbnb beds are pretty firm, so it's worth mentioning.
Location is convenient to a lot of things, which is great--about a mile walk from the V&A, Museum of Natural History, etc. The corner that the building is on is kinda noisy, which is only an issue b/c there is no AC or fan, so sleeping with the windows open in the summer is not optional. There's a chain grocery nearby, and a cute little French grocer/cafe right downstairs on the corner, with another, similar grocer up the block.
Overall, a good place for a short stay in London, and you will be in good hands.