Louis Simonds continues to describe London townhouses in his book, An American in Regency England:
The plan of these houses is very simple, two rooms on each story; one in the front with two or three windows looking on the street, the other on a yard behind, often very small; the stairs generally taken out of the breadth of the backroom. The ground-floor is usually elevated a few feet above the level of the street, and separated from it by an area, a sort of ditch, a few feet wide, generally from three to eight, and six or eight feet deep, inclosed by an iron railing; the windows of the kitchen are in this area. A bridge of stone or brick leads to the door of the house.
The front of these houses is about twenty or twenty-five feet wide; they certainly have rather a paltry appearance - but you cannot pass the threshold without being struck with the look of order and neatness of the interior. Instead of the abominable filth of the common entrance and common stairs of of a French house, here you step from the very street on a neat floorcloth or carpet, the wall painted or papered, a lamp in its glass bell hanging from the ceiling, and every apartment in the same style - all is neat, compact, and independent, or, as it is best expressed here, snug and comfortable - a familiar expression, rather vulgar perhaps, from the thing itself being too common.
To read more about townhouses during this era, click on the following:
English Heritage Townhouses Selection Guide: Domestic Buildings
Here's an interesting historical detail, as described in The Hidden Dimension by Edward T. Hall:
...rooms had no fixed functions in European houses until the eighteenth century. Members of the family had no privacy as we know it today. There were no spaces that were sacred or specialized. Strangers came and went at will, while beds and tables were set up and taken down according to the moods and appetites of the occupants ... In the eighteenth century, the house altered its form. In French, chambre was distinguished from salle. In English, the function of a room was indicated by its name - bedroom, living room, dining room. Rooms were arranged to open into a corridor or hall, like houses into a street. No longer did the occupants pass through one room into another. Relieved of the Grand Central Station atmosphere and protected by new spaces, the family pattern began to stabilize and was was expressed further in the form of the house. p.104
See the illustration of a Georgian terraced house below.