Northumberland House (painting) in the context of "Equestrian statue of Charles I, Charing Cross"

In British usage, the term townhouse originally referred to the opulent town or city residence (in practice normally in Westminster near the seat of the monarch) of a member of the nobility or gentry, as opposed to their country seat, generally known as a country house or, colloquially, for the larger ones, stately home. The grandest of the London townhouses were stand-alone buildings, comparable to the hôtel particulier, which notably housed the French nobleman in Paris, as well as to the urban domus of the nobiles of Ancient Rome. but many were terraced buildings.

British property developers and estate agents nowadays often use the term "townhouse" for terraced buildings, following the North American usage of the term, to aggrandise modest dwellings and attract buyers who associate the term "terraced house" with the cheap terraced housing built in the Victorian era to accommodate workers. The upmarket Victorian terraced housing, which can be found around many of London's garden squares, seems to be widely forgotten in these circles.

Northumberland House (also known as Suffolk House when owned by the Earls of Suffolk) was a large Jacobean townhouse in London, so-called because it was, for most of its history, the London residence of the Percy family, who were the Earls and later Dukes of Northumberland and one of England's richest and most prominent aristocratic dynasties for many centuries. It stood at the far western end of the Strand from around 1605 until it was demolished in 1874. In its later years it overlooked Trafalgar Square.