The announcement at the Commonwealth conference in Perth of changes to the rules of succession suggested it was a done deal. David Cameron has the agreement of the heads of government of the other countries of which the Queen is head of state (the realms). But all the realms now have to change their laws, in a process which will take years.
It has been a longstanding aim of British governments to end the discrimination in the laws of succession. 11 private member’s bills have been introduced into Parliament to reform the Act of Settlement. Successive governments have supported the change in principle, but have said that only the government could legislate; because only the government could negotiate with the other realms. But getting all the realms signed up seemed daunting.
Gordon Brown went to the Commonwealth conference in 2009 with the same objective as David Cameron, but failed. Since then there has been a lot of work behind the scenes to get the other 15 realms on board. The tide of goodwill towards the monarchy following the royal wedding in 2011 and the Queen’s diamond jubilee in 2012 provides the perfect window of opportunity to make the change.
The fanfare of David Cameron’s announcement is intended to give maximum momentum to a project which is not all plain sailing. The UK can give a lead, but cannot legislate for the other 15 realms. In Australia the six states claim a separate relationship with the Crown, and the change may require their separate consent. In Canada the federal government will certainly have to gain the consent of the provinces, including Quebec. In both countries it will revive the republican issue.
Questions will also be asked about why the discrimination against Roman Catholics is only to be partially removed. The prohibition on the Monarch being a Catholic will remain. Even if it were removed, no Catholic could satisfy the requirement to be ‘in communion with’ the Church of England and thence Supreme Governor of the Church of England. Catholics in Britain might be willing to accept that, although their numbers are now broadly equal to Anglicans. While welcoming the removal of the ‘unjust discrimination’ against Catholics, the Archbishop of Westminster, Vincent Nichols, said ‘At the same time I fully recognise the importance of the position of the established church [the Church of England] in protecting and fostering the role of faith in our society today’. But in the 15 realms Catholics outnumber Anglicans by three to one, and they may be less understanding.
The ending of male primogeniture is less controversial. Most other European monarchies have changed their rules of succession already to make them gender neutral. Sweden changed their law in 1980, Holland in 1983, Norway in 1990, Belgium in 1991, Denmark in 2009 (with a referendum), Luxembourg in 2011. Only Spain, Monaco and Liechtenstein retain male primogeniture.
More information:
The Constitution Unit Blog 
I’m not a Catholic,so there’s probably a good answer to this query, but does Matrimonia Mixta, Apostolic Letter 1 October 1970, present a problem ?
“Furthermore, the Catholic partner in a mixed marriage is obliged, not only to remain steadfast in the faith, but also, as far as possible, to see to it that the children be baptized and brought up in that same faith and receive all those aids to eternal salvation which the Catholic Church provides for her sons and daughters.”
Does ‘as far as possible’ mean that a Catholic parent could avoid the obligation if the child were heir to the throne, and Catholics were still barred from the succession ?
David Bentley