Tiny Houses North Wales (motto: Tiny in space but not in quality) is a family-run business in Llanrwst in the Snowdonia national park. You can see more images of the company's first model on its website here, with designs running from 12ft to 22ft long, sleeping up to six adults, and on a variety of chassis.
This first house is 6m x 2.4m with a bathroom with power shower, sleeping area in the upper loft and convertible bed/sofa. Other features include an LPG gas combi boiler and the whole thing is insulated with sheep's wool. Again, much more detail on the site.