Whatever the highs and lows endured by our political rulers over the past 12 months, it has been an excellent year for the Queen.

She may not have enjoyed the flag-waving adulation of her diamond jubilee in 2012, and she may be travelling a little less these days, but there is no doubt she has seen out 2014 triumphantly.

She has just been voted our most moral leader, beating the Archbishop of Canterbury, the Prime Minister, the rest of her family and the Pakistani schoolgirl Malala Yousafzai in a YouGov poll.

More revealingly, she was the biggest television ratings success over Christmas, with her annual message to the nation attracting 7.8 million viewers, more even than the Irish comedy Mrs Brown's Boys and the evergreen EastEnders.

An 88-year-old great grandmother mulling over Christ as a "role model of forgiveness" may not be obvious box office, but the Queen, alone among our public figures, can get away with mixing God and politics. She can get away with almost anything.

Her appeal in her broadcast to Scots to heal their differences in the wake of the referendum made headline news, as did her surprise intervention in the days before September 18, when she urged voters to "think very carefully about the future". She was regarded then as the ultimate trump card by Unionists, many believe she helped sway the outcome - and no one told her to mind her own business.

On every side of the political divide, her words are taken seriously because of her immense popularity. If she hinted at her affection for Europe we would probably vote to stay in the EU. Considering her royal prerogatives are largely ceremonial, she exudes quiet yet great power.

Given all the above, it may seem pointless to debate reform of the monarchy, but there is no time like the present. The Queen owes her place in our affections to her longevity. Of course she is respected, even loved, for the way she carries out her duties, but it is her permanence that really cements her status.

Next year, on September 9, she will overtake Queen Victoria as Britain's longest serving monarch, a result of good luck (those genes that kept her mother going strong until 101) and bad luck (the premature death from lung cancer of her father, King George VI, at 56).

She came to the throne in her twenties and has been the regal backdrop to most of our lives, her reign the only one most of us have known. If her health holds out, and there are no signs it won't, her heir, Charles, who is 66, could be in his late seventies when he becomes king.

At the age when most of his subjects have long retired, he will be expected to inject vigour into the role and redefine its meaning for new generations. But he is already unpopular, seen to provide poor moral leadership (he scored only eight per cent in the YouGov survey compared to the Queen's 34 per cent), and is much less favoured than Prince William, Prince Harry and the Duchess of Cambridge, not to mention his mother.

Although he has brought some of this on himself, with his rich man's eco and organic obsessions and his sometimes disdainful manner, it is not his fault that his life has been spent waiting for the country's most cherished citizen to die.

The same fate awaits Prince William. Currently riding high in opinion polls, sometimes even outflanking his grandmother, he too will most likely be an elderly man when he is crowned. Given his family's life expectancy, he may be well into his sixties, his wife will no longer be a fashion plate, and both will be judged on what they have done, not on who they are.

And so it will go on. Baby George could be, say, 66 with a receding hairline and the quaint penchants of a spoilt and idle pensioner when he eventually fulfils his destiny.

The days when people lived three score years and ten, and when kings were occasionally claimed early (by disease or war), are mostly gone and, barring tragedy, there is unlikely to be another youthful coronation to match the Queen's, or another monarch long to reign over us.

So why not change the rules? Abdication is not a word we like in this country; it smacks of crisis and harks back to a painful period in our history. But we could introduce a retirement scheme that is relevant to the royal succession.

It might be a bit late to benefit Charles, and we would probably have to skip him altogether if it were to work for William, but what of the kings and queens of the future? There are precedents: Spain's King Juan Carlos stood down in June, at a relatively young 76 to make way for his son. In 2013, Queen Beatrix of the Netherlands handed over to her son, as did King Albert of Belgium in the same year. The monarchies in those countries seem to have survived these recent transitions and remain resilient.

Could we not use them as our template? How Charles must envy his European counterparts, all younger than him and already the crowned heads of their states. Six years ago he became the longest-waiting heir to the throne in British history, out doing his great great grandfather Edward VII.

He has admitted to being impatient and is reported to have said to his brother-in-law Charles Spencer at the eighth Earl Spencer's funeral: 'You are fortunate enough to have succeeded to the title when still young.'

While he is hard to pity, with his position, privilege and palatial residences, his is not a fate that serves any purpose. If he had been an heir with an end date, with the certainty of a career-length reign, his whole life would have been different.

As a king in preparation, rather than just in waiting, he might have been more focused on royal matters, more neutral, less controversial, less bored maybe, and less tempted to fire off letters to ministers and lobby for his pet projects.

Charles is seen as an eccentric but basically a kindly, harmless one; imagine an heir with 50 years to promote more odious causes.

Increasingly, we demand value for money from our royals and we ask that our monarchs perform some useful role in society. But if they have a job to do, surely they should do it when they are at their peak, and not when their energy is sapped and their best years are behind them.

We have postponed any meaningful discussion of the Windsors because of the Queen's remarkable sprightliness; we can't quite believe she won't always be here. So revered has she become with age that even republican Scottish Nationalists have had to feign allegiance. And the older she gets, the more popular she is, and the monarchy with her.

But the institution will be more vulnerable without her and there must be a plan somewhere, dreamt up by top constitutional experts behind closed doors, to address the Charles problem and prevent it recurring with each succession. If there isn't a plan, perhaps it's time to make one.