A great-grandchild to the Queen — her third — the Duke and Duchess of Cambridge’s baby will one day be Head of the Armed Forces, Supreme Governor of the Church of England, head of state of 16 countries and possibly if the role is maintained in the future, Head of the Commonwealth which covers 54 nations across the world.
If the baby, which will be heralded as a symbol of the continuation the monarchy, follows after the Prince of Wales and the Duke of Cambridge as Sovereign, he or she will be the 43rd monarch since William the Conqueror obtained the crown of England in 1066.
The baby is also 41st in direct line of descent from Egbert, King of Wessex, who ruled from 802 to 839, and, following Charles and William, will be the eighth monarch to descend from Queen Victoria, including the abdicated Edward VIII.
William’s firstborn will be great-great-great-great-great-grandchild of Queen Victoria.
Their arrival will see uncle Prince Harry move from third to fourth in line to the throne, while the Duke of York is to shift down to fifth and Princesses Beatrice and Eugenie to sixth and seventh place.
The last time a still-serving monarch got to meet a great-grandchild born in direct succession to the crown was nearly 120 years ago.
Queen Victoria, who reigned until 1901, was still sovereign when her great-grandchild Edward VIII, who later abdicated, was born third in line in 1894.
His brother George VI was also born in Queen Victoria’s lifetime, arriving fourth in line in 1895.
The last great-granddaughter of a still-serving sovereign born in direct succession on the male line was their sister Princess Mary in 1897.
The Queen has already welcomed her first great-grandchild, Savannah Phillips — the daughter of Peter and Autumn Phillips — but Ms Phillips was born only 12th in line, being born down the female line as a granddaughter to the Princess Royal.
Her second great-grandchild, Savannah’s sister Isla, was born in March 2012.
The baby is also a first grandchild for heir to the throne Charles, although he has had plenty of practice in the role as wife the Duchess of Cornwall already has five grandchildren. He or she will also be a first grandchild for the Middletons.