The Queen is head of the sixteen realms which make up the Commonwealth. We are in Perth, Western Australia, where The Queen is on tour – before opening the Heads of Government Meeting. It is a 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 might 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 programme shows.