First, we have a drawing room from 1910:
The room is based on one in a semi-detached house somewhere like Golders Green, and is very light thanks to both the French windows and the electric lights.
Next comes the 1935 'dining lounge' of a purpose built flat:
Note the telephone, the record player and the fancy wall-lights.
Our third visit is to the open-plan living/dining room of a 1965 town-house:
Note the groovy television, the candle-based table decoration and the polished stairs that have to be a trip hazard.
Finally, we have a 1998 loft-style apartment:
Note how untidy the kitchen area and stairs are, when it appears that the guests haven't even arrived yet.
You can view the rooms as they are the rest of the year here, here (flash view) or here (360 degree view). More details about the rooms of the middle classes, and about historical Christmases, can be found in books from the museum shop.