I had such an amazing time at Charlotte's place that I was sad to leave. First and foremost, Charlotte is a wonderful person - thoughtful, optimistic, witty, sincere, energetic. When I came back from walking all around London I enjoyed having something to drink and talking with her in the beautiful drawing room. She made me feel right at home, as if I were visiting a relative, and had very interesting stories to share about her trips, adventures, and life in general.
I really liked the flat as well as my room and shower room. Everything was comfortable and cozy. I cannot add more positive feedback to what others have said. One thing though, I was very excited about, was that I could hear the Big Ben from my bed before I went to sleep!
Charlotte keeps everything clean, tidy, and makes you feel welcome. She has even put together a folder with "everything you'll need to know" - from bus lines and eateries, to the best ice-cream in London - and a number of guides of London. She also gave me good ideas that made my walks around the city much better.
Regarding the location of the flat, I do not think there is a better one. There is a bus around the corner that takes you everywhere. Also, Victoria Station is 7 minutes away, which is very handy to connect to any airport or train station. I also enjoyed walking - walking from the apartment to Westminster Abbey/Parliament is lovely or to St. James Park.