NORWAY, like Britain, has a constitutional monarchy. The present head of the Norwegian royal family is King Harald V, who succeeded his late father, King Olav V, to the throne on January 17, 1991. He was born in 1937 at Skaugum, the estate just outside the Norwegian capital, Oslo, which is still the home of the royal family. The King's family has ruled Norway since the dissolution of the union with Sweden in 1905. King Harald V studied political science, history and economics at Balliol College, Oxford University, and married commoner Sonja Haraldsen in 1968. Queen Sonja was also born in Norway in 1937. At the time of the marriage, she became a crown princess and, on her husband's succession, became the first Nowegian queen for 53 years. Since the early 1990s, she has helped with the planning for the Winter Olympics to be held in Lillehammer next year. Her husband represented Norway several times in sailing at the Olympic Games and world championships. He has also served as honorary chairman of the Lillehammer Olympic Organising Committee. The couple have two children, Crown Prince Haakon, 19, and Princess Martha Louise, 21.