Alhambra Hotel is exactly what you need for a short stay in London; a clean and reasonably spacious room, a compact newly refurbished bathroom, nice breakfast and a friendly staff, all at a very reasonable price.
When we're in London we just use the Hotel for sleeping, and Alhambra is perfect for that. The location a 5 minute walk from one of the most important train stations, Kings Cross St. Pancras, is the optimal starting point for excursions in London.