Reasons I thought, and still think, it is of the 'townhouse' type structure (US terminology, and I'm not sure if townhouse means the same thing in the UK.):
(a) Entrance corridor is long but not wide. Individual houses tend to have wider entrance hallways.
(b) The garden (or yard, for US terminology) in the back is small and does not look like it spans the perimeter of the entire house. If it were an individual house, I doubt she would complain that the 'garden' is so small because she would have the entire house perimeter, including the front garden (yard).
Her house could also be the 'end unit' in a row of townhouses directly on a street, so only connected to another house on one side. In that case, though, she could have a larger garden because it could span the side as well, unless the side were directly flush with the street.
Even if her house is an end-unit, it is still considered a townhouse by US terminology.