Nicola's place is a beautiful cottage in the Pimlico area. Be aware that it is a historic building, so it may be smaller than what you're used to. It features a tight spiral staircase, but it isn't much of an inconvenience.
My family and I enjoyed our time staying in the cottage! It was spotless and Nicola & Jason were very responsive to all of our needs during our one week stay. I would highly recommend staying here as it is close to all of the major sights in Central London, but is a nice quiet neighborhood. I would definitely come back!