From a quick survey, the reasons are twofold. First, politicians are jealous of their political powers to aggrandise all within their ambit, so embellishing the royal Head of State (unlike the practice of the American presidency) benefits neither them nor their masters, the electorate. Second, the Westminster parliamentary system itself forbids the prime minister is assume de jure (if not always de facto) all of the appurtenances that pertain to the Head of State.
On a more theoretical basis, Austrian economist Hans-Hermann Hoppe has examined the effectiveness of both monarchies and democracies to restrain the growth of government and, of the two, he credits the former with a better relative record for preserving individual liberties and fostering an atmosphere of economic prudence.
All of which leads me to wonder why classical liberals are so often enamoured of the republican ideal. One can understand their inability to appreciate a Tory reverence for tradition and continuity, yet why do they so cavalierly dismiss the public choice arguments which demonstrate that limited government in the age of the Welfare State is held hostage to democratic fortune?
To all who see in politics the culmination of human effort and the end of all earthly activity, this essay is written in tribute to the Roman slave who, while accompanying the conquering general in his chariot, held a wreath of laurel over the commander’s head while whispering into his ear, ‘Remember, you are only a man...’
Public choice theory reminds us to-day that in the absence of mindful supervision, the State and its servants are liable to aggrandise themselves while encroaching on our liberty.
Click here for my full argument at the Adam Smith Institute.