King, Queen (non-consort) and monarch used to be one and the same in my mind until I read the article, Palace Intrigues. In Palace Intrigues, the assertion was made that all modern political systems have monarchs in the sense that a monarch is the entity with the ultimate legal power in a political space. These entities are usually not called kings, or queens or monarchs. This dissociation of king or queen from the ultimate legal power in a political space implies that there are kings and queens who are not monarchs. What to do?
Kings and Queens who are no longer monarchs who want to still retain some meaningful power can only do so within the legal framework the people have set-up. Most people no longer acknowledge the palace as the ultimate center of legal authority for all people in a political space. Some spaces are even without palaces. There are several reasons for this rejection. One reason is that many people see the palace as dictatorial, unduely priviledged and non-benevolent. Another reason is that most important spaces have become heterogeneous. The people who are ethnically affiliated with a palace may not mind the authority of the palace. But the people who are not ethnically affiliated with a palace may mind its authority (they often claim to have their own kings or queens to whom they owe allegiance).
In England, after several fights between Kings and Parliament (e.g. King Charles I and Parliament, King Charles II and Parliament, King James II and Parliament), a compromise was reached when King William III (James II's son-in-law) and his wife Mary II (James II's daughter) accepted Parliament's offer to restore the throne to them. The English Bill Of Rights was signed. Parliament was granted the right to make laws and levy taxes (the two most important expression of power of a monarch). The King's or Queen's ability to raise an army (the only remaining expression of power) was conditioned on consent from Parliament. Thus England's political system was changed to a limited monarchy.
In modern times, England's royal family has been able to re-invent itself and has become globally relevant. The world knows if a member is pregnant, has given birth, is marrying, is sick, etc. Only England's royal family is able to draw grand global attention to the wedding of a prince who is fifth (may soon be sixth) in line to the throne. The kings and queens of most of the spaces Britain conquered (if there are still kings or queens in the spaces) have not fare that well. It is a struggle just to get even their immediate subjects to acknowledge their reign in the context of a larger political system set up by Britain. These are kings and queens who have resigned themselves to the complacency of being ceremonial kings and queens. Kings and queens who are no longer monarchs.