Mother planning 3 day trip to London in late Jan with adult son and daughter. Ideally looking for ideas on a centrally, well located 4 star hotel (Knightsbridge, Mayfair, etc) that would have the type of suite that would allow us to all stay in one room. So, other that a bedroom, it would have a second bedroom or pull out sofa in a separate room. one bathroom would suffice. Budget could accommodate up to 300 pounds per night. Any good ideas out there? Many thanks.