The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret. The coolest royal sister flower of the twentieth century – Elizabeth II and his sister Princess Margaret.