The so-called "tiny house movement" is, in this Daily Mail article, being treated as a big deal. Perhaps it is in the U.K., where the Mail is located.
In the U.S. small homes are old news; RV parks all over the southern U.S. have tiny houses (without wheels) parked in them, called in the trade "park models." Designed to be towed to the site and set up more-or-less permanently, they are factory-built.
Unlike traditional RVs -- motorhomes, trailers, etc. -- a park model has no holding tanks for potable, gray and black water. Definitions: "Potable" is fresh water for cooking and washing, "gray" water is runoff from sinks and showers, "black" is from toilets.
A park model has the same sort of toilet, water heater, refrigerator, and HVAC system you'd have in a house or apartment. Mobile RVs have those features too, but they function in different fashions. Think of a park model as a factory-built, free-standing one-bedroom, one-bath apartment.
Normally park models locate in RV parks and "mobile" homes in mobile home parks, they are rarely mixed in one park. A park model RV is distinguished from the misnamed "mobile home" or manufactured home by virtue of its small size. Typically, a park model must be smaller than 400 square feet and no wider than 8.5 feet.
That puts park models squarely into what the Mail calls the "tiny house" category. To gain extra room, some park models have a low-ceiling sleeping loft or mezzanine. See, for example, Oregon's regulations governing park models.
