The crazy thing about all of the different innovative housing ideas that we show is how design is so affected by the rules. So in America you can design a shed or a recreational vehicle (why so many tiny houses are on chassis) or a mobile home or a trailer or a park model or a HUD home. All of these are subject to different building codes and more importantly, to different zoning bylaws that determine where they can go.
It is much the same in the UK, with the difference that where in America, trailers are considered somewhat downmarket, there they are called Caravans. They can be quite upscale and wonderful, like this one at Brockloch bothy, built by Sam Booth of ECHO.