Tŷ unnos (pl.: tai unnos; English: one night house, also hafodunnos) is an old Welsh tradition that has parallels in other folk traditions in other areas of the British Isles. It was believed by some that if a person could build a house on common land in one night, the land then belonged to them as a freehold. There are other variations on this tradition, for example that the test was to have a fire burning in the hearth by the following morning and the squatter could then extend the land around by the distance they could throw an axe from the four corners of the house. Origins From a period spanning the seventeenth to the beginning of the nineteenth centuries, the expansion of the Welsh population combined with poverty brought about a series of incidents of squatting on isolated patches of land in the most rural parts of Wales. The practice arose because of the pressure of the lack of land due to the land enclosures of the period, and the taxation laws established by landowners. Family units paid taxes based on the land they inhabited, so families with adult and married children faced paying additional taxes on a second home, even if it was on the same land. Legal status Tŷ unnos has no status in English common law (the legal code which applied to England and Wales in this period), although there is some tradition of legal discussion about the point at which land occupied by squatters without title may be regarded as a legitimate possession. This legendary belief may bear some relation to genuine folk customs and actual practices by squatters encroaching on common or waste land. The tradition may have provided squatters with a sense that their actions enjoyed some legitimacy conferred by an older code of laws more in tune with values of social justice than the supposed "Norman yoke". The customary practice has no foundation in the Common Law regarding land usage as it applies in England and Wales. Many localities in Wales and England have a house or houses which may be identified as a one night house in local folklore. These may in fact be properties that were originally built by squatters and may be constructed in a vernacular building tradition using locally available materials. The Ugly House (Tŷ Hyll) is a celebrated example in Snowdonia. Many of these legends seem