Our family (kids aged 5;4;2) stayed together with two nannies. The house was as comfortable and pleasant as it could be.
Plenty of space, well equipped kitchen, cosy reception. My wife and I slept on the top floor and had good privacy without being too far away. Kids 5 and 4 had a large room they could play in. Kid 2 had room to himself, with a cot that we forgot asking for so Andy came especially just to provide it.
The neighborhood is splendid. Very silent and private, while at the same time being close to all the museums, shops and attractions of Knightsbridge and South Kensington, the tube is very close, as are several bus lines. The park is as close as can be.
Great place. Looks in life even better than in the pictures.