Niue celebrated 50 years of self-government on Saturday, with Britain's King Charles issuing a congratulatory video, but the Pacific Island state is excluded from this week's Commonwealth leaders meeting, and its prime minister wants change. Known informally as the Rock of Polynesia, Niue was settled by Samoans in 900AD and has a population of around 1, 500. Yet as Samoa hosts the 75th Commonwealth Heads of Government Meeting, where leaders and officials from 56 countries with roots in Britain's