The abdication of Queen Margrethe of Denmark in favour of her son Frederik is a sign of a sensible constitutional monarchy. The 82-year-old queen felt “time was running out and the ills were increasing”. It was best to hand over now. In this, Margrethe follows the abdication over the past decade or so of monarchs in the Netherlands, Belgium and Spain. It is now being pressed on the 77-year-old Carl Gustaf of Sweden. Heredity is an indefensible basis for the holding of high office. It survives only in the direst of dictatorships and the most liberal of democracies. Of course, in democracies it is impotent, merely embodying in one person the ceremonial functions of a monarchical head of state. Its mystique survives simply by remaining popular. At the time of Elizabeth II’s platinum jubilee in 2022, there was quiet talk of her abdicating in favour of Charles. The nation faced a repeat of the long incapacity of the elderly Queen Victoria. Such talk was drowned out by sheer affection for the Queen. She adamantly performed her duties to the end – even appointing Liz Truss standing up – and resolved the issue by dying shortly afterwards. To radicals, a geriatric European monarchy entombed in what amounts to palatial care homes might be welcome. It reduces the risk of accidents and scandals, such as those that afflicted Spain under Juan Carlos, or meddling in democratic politics. But it renders the institution vulnerable to incapacity and unpopularity. As the US and French presidencies show, headship of state requires the ability to cohere and represent an entire people. Even without the burdens of government, it can be difficult to do this, as Queen Elizabeth found during the death of Diana. Sweden’s parliament has steadily stripped its king, Carl Gustaf, of all roles but the most vacuously ceremonial. Abdication is the obvious answer. It signifies that a head of state is not a waxwork, but must be a hard-working master of ceremonies. Growing old should never be a bar to work, but age does not negotiate. Britain’s King Charles, after a long apprenticeship, has proved an active and popular figure in his term of office. He has shown no sign of ageing, other than perhaps his limp Christmas message. He is certainly entitled to a substantial reign after waiting so long. But not to death. Charles has a successor, William, well-trained and evidently suited for the job. The abdication of Beatrix of the Netherlands to Willem-Alexander in 2013 was an ideal precedent. It prompted an outpouring of gratitude for her reign, a welcome for her son and a stronger monarchy as a result. The flamboyant conductor André Rieu had the Dutch joyously dancing in the streets in their thousands. There was none of the lugubriousness inevitably attached to Britain’s succession through death. Abdication also indicates a nation able to keep its institutions fit for purpose. In slimming down the royal family, Charles has wisely indicated a desire to end such damaging princely sagas as those of Andrew and Harry. But he must surely go further in updating the office he should one day hand over to his son. We need modern-day clarity, not least because the list of archaisms is endless. The Anglican coronation was antediluvian in a now largely faithless country. It did not even mention the monarch’s serving in a democracy. The royal estate in London is hugely overblown. Buckingham Palace gardens should be a public park. Compared with other “bicycling monarchies”, Britain’s is on a scale out of reasonable proportion, a hostage to future misfortune and unpopularity. This is a conversation the next British government should be having with the king. The present British political community seems equally unable to handle constitutional reform. One of its two Houses of Parliament still reserves 91 seats for members sitting by right of heredity, and 26 seats for bishops of what is now a minority church. There should at least be 26 mullahs, in order to be fair. We are no longer governed by monarchs. That the aristocracy still enjoys these hereditary seats beggars belief. Britain is one of the few countries on Earth where legislative power, however modest, is still awarded by parentage or religion. Equally indefensible is that all members of the upper house other than bishops should be considered fit for such power until they die. It seemed harmless when introduced in 1958 for much-needed “working peers”. Since then the abuse of the peerage by successive prime ministers – well before the much-criticised appointments by Boris Johnson and Liz Truss – clearly demands drastic change. The current corruption of peerages, honours, public appointments and government contracts makes Britain a laughing stock when it chooses to accuse foreign regimes of similar corruption. Yet there is not the slightest sign of reform. These may not be the most pressing issues confronting British government today. It is easy to shrug and say, if we were creating a new constitution, we would not start from here. But we are not even starting. There is no whisper of reform in the air. We are left saying merely, thank you, Denmark. Simon Jenkins is a Guardian columnist