Wales, Government of. Wales is one of four divisions of the United Kingdom, which is both a parliamentary democracy and a constitutional monarchy. The monarch is the head of state, but the prime minister and a cabinet of senior politicians govern the country. For historical reasons, Wales is called a principality (country ruled by a prince). The reigning monarch of the United Kingdom usually gives the title Prince of Wales to his or her eldest son, the heir to the throne (see Prince of Wales).