For years, supporters of the monarchy have claimed that the monarch represents a significant constitutional check on our politicians and is politically neutral. The British Prime Minister Boris Johnson's request to the Queen to prorogue (essentially suspend) parliament for a period, whatever your thoughts are on Brexit, highlighted this contradictory claim. Supporters of the monarchy have claimed often that "It's not the power the Queen has, but the power the Queen denies to politicians." So if there's anyone who should not be surprised at the anger being directed at the Queen for her decision to follow hundreds of years of constitutional conventions, it should be those supporters.
It seems the basis for this claim is to reassure the public that the Queen is more than just a figurehead, that as Sovereign the Queen has some leeway when it comes to decision making on these issues. In fact, as the prorogation request has shown, the Queen is guided by an essential tenet of Westminster parliamentary democracy, expressed in our own Cabinet Manual as "the Queen reigns, but the government rules, so long as it has the support of the House of Representatives." In this case, the key question is whether Boris Johnson and his government have the continued confidence of the House of Commons. On the basis that he does, having not lost a vote of confidence, the Queen's only course of action is to act on his advice and prorogue parliament as requested. That is a longstanding (and hard-fought-for) principle that if the Queen were to deviate, would throw out the "constitutional" part of a constitutional monarchy - a monarchy where the Sovereign is restricted by constitutional rules and conventions. For so-called constitutional monarchists that should be a major problem.
Critics of the move make the argument that the prorogation is only occurring to prevent debate on Brexit, which is now due to occur with or without a deal with the EU on October 31. Naturally, if you're opposed to Brexit, the Queen's approval of prorogation is seen as a capitulation to Boris Johnson and his agenda to deliver Brexit. But the fact is that constitutional convention has always been that the Queen followers her Prime Ministers' advice. The only leeway the Queen really has is the soft power wielded behind closed doors, which we will never know about. That is an area worth focusing our attention on.
For New Zealand Republic's part, we have always pointed out that the claim that the Queen is all-powerful or has any real discretion, even when the reserve powers apply, is simply false. We have consistently pointed out that, except for when the reserve powers apply - when a Prime Minister and his or her government have last the confidence of parliament - the Queen does whatever she is advised to do. The chickens are coming home to roost for those who have claimed otherwise.
But would an elected, largely ceremonial head of state, such as New Zealand Republic's proposal for New Zealand, be any different? It depends. They would have available to them through the ability to signal disapproval more clearly - there are a number of precedents of non-executive heads of state resigning instead of approving actions they don't agree with. Even heads of state with constitutionally outlined leeway, such as Ireland's president, are bound by constitutional conventions as the Queen is. Whatever the position, any anger over the prorogation should be directed at the requestor, not the requestee who is simply following constitutional convention.