Perth Agreement

The Perth Agreement was made in Australia in 2011 by the prime ministers of what were then the sixteen states known as Commonwealth realms, all recognising Elizabeth II as their head of state. The document agreed that the governments of the realms would amend their laws concerning the succession to their shared throne and related matters. The changes, in summary, comprised:

• Replacing male-preference primogeniture (under which males take precedence over females in the royal succession) with absolute primogeniture (which does not distinguish sex as a succession criterion), for those born after 28 October 2011;
• Ending disqualification of any person who had married a Catholic;
• Establishing that only the six people closest to the throne require the monarch's permission to marry.

The ban on non-Protestants becoming monarch and the requirement for them to be in communion with the Church of England was not altered.

The Agreement was signed in October 2011 in Perth, Australia, which hosted the biennial Commonwealth Heads of Government Meeting (CHOGM). The institutional and constitutional principles of Commonwealth realms are shared equally as enacted in the Statute of Westminster 1931, which made the process of implementing the agreement lengthy and complex.

By December 2012, all the realm governments had agreed to enact it. New Zealand chaired a working group to determine the process. The Commonwealth realms – at the time including the United Kingdom, Canada, Australia, New Zealand, Jamaica, Barbados, the Bahamas, Grenada, Papua New Guinea, the Solomon Islands, Tuvalu, Saint Lucia, Saint Vincent and the Grenadines, Belize, Antigua and Barbuda, and Saint Kitts and Nevis – are independent of each other, while sharing one person as monarch in a constitutionally equal fashion. (Barbados has since become a republic.^[1]) The working group later affirmed that, across all these realms, appropriate laws were passed and came into effect, and the Deputy Prime Minister of the United Kingdom reiterated this on 26 March 2015.^[2][3][4] Canada's law was challenged in court but has been upheld.^[5][6]

On the day the changes came into effect in March 2015, the first of the persons affected by the headline provision were the children of Lady Davina Windsor, the elder daughter of Prince Richard, Duke of Gloucester and Birgitte, Duchess of Gloucester; the succession positions of Lady Davina's son Tāne (born 2012) and daughter Senna (born 2010) were reversed, Tāne becoming 29th and Senna becoming 28th in line.^[7]