18 Stafford Terrace, Kensington, London

(Visited as part of “Open House London.”)
18 Stafford Terrace was the home of Victorian cartoonist Edward Linley Sambourne, with his wife, children and live-in servants. The house is essentially unaltered since then, and presents an almost unique Victorian interior, dimly lit and with the expensive hand-made wallpaper almost covered by framed drawings, prints and paintings, and a dense clutter of furniture and collectible objects. There is stained glass in some of the windows.
On the free Open House day, I got to see (after queueing) the ground floor, part of the stairwell, and the Victorian loo. If you visit at another time, the 1.5 hour paid conducted tours go to all five floors. The contents of the basement are long gone and replaced by meeting room, shop, and modern toilets.
The house is now owned and operated by the Royal Borough of Kensington and Chelsea.
This should be an essential visit if you are interested in Victoriana.