The queen is head of the 16 realms that make up the Commonwealth. In Perth, Western Australia, Queen Elizabeth is on tour before opening the Heads of Government Meeting, which is especially important for the monarchy. The Commonwealth countries are being asked to change the rules of succession so that a first-born girl may inherit the crown. If it's approved, it will be the single biggest change to the monarchy for centuries. At the age of 85, the queen remains undaunted by long-haul travel -- as this program shows.