Well, over the last hundred years we've gone from "the divine right of the King to rule his subjects" to "the Monarchy brings in money by attracting tourists to the UK". Who knows where we'll be in another hundred years.
There is more to the British monarchy than tourism, but even so, it is worth noting (emphasis mine):
'This is the doctrine of "the divine right of kings". According to it, in its rigour, in a State once monarchical, monarchy is forever the only lawful government, and all authority is vested in the monarch, to be communicated by him, to such as he may select for the time being to share his power. This "divine right of kings" (very different from the doctrine that all authority, whether of king or of republic, is from God), has never been sanctioned by the Catholic Church. At the Reformation it assumed a form exceedingly hostile to Catholicism, monarchs like Henry VIII, and James I, of England, claiming the fullness of spiritual as well as of civil authority, and this in such inalienable possession that no jot or tittle of prerogative could ever pass away from the Crown. [...] Suárez argued against James I that spiritual authority is not vested in the Crown, and that even civil authority is not the immediate gift of God to the king, but is given by God to the people collectively, and by them bestowed on the monarch, according to the theory of the Roman lawyers above mentioned, and according to Aristotle and St. Thomas.' [0]
Magna Carta was issued in June 1215 and was the first document to put into writing the principle that the king and his government was not above the law.
Looks like you're a tad out of date there.
A hundred years ago King George V inherited the throne at a politically turbulent time, with the House of Lords exerting pressure to bend the King to their ends and grant a dissolution .. very much the political tail wagging the King dog rather than vice versa.
Quite apart from Magna Carta, the outcome of the Civil War determined very effectively whether the British Monarch had divine right to rule. In the negative.
With a regular reminder to the reigning monarch just outside the House of Commons in Westminster, a statue of Oliver Cromwell. Apart from the awful, awful acts that he commissioned against the people of Ireland, he also ensured that the concept of parliamentary supremacy against a sitting king that ignored or agitated against it, was demonstrated in a fairly direct way, the execution of King Charles I (there’s a statue of Charles I across the way, just to make sure you don’t miss the message)
