The chances of Prince William leapfrogging his father to the throne increased dramatically this week. As the Prince of Wales heads further and further into unconstitutional waters by demanding his letters to government ministers remain private, William started to look like a much more eligible candidate for kingship.

Attorney General Dominic Grieve's stay on publication of Prince Charles's controversial correspondence - there are said to be 27 'particularly frank' letters - does nothing beyond provide a temporary respite for the beleaguered heir to the throne. Indeed, while Grieve may have appeared to be throwing a protective cloak around Charles's shoulders in denying the Guardian's bid to disclose the prince's interfering in government business, his words said otherwise.

To state that publication of Charles's letters to ministers 'would undermine his ability to rule' is to issue a devastating critique of the prince's improper use of influence over impressionable MPs. But there, Grieve said it.

Under cover of what appeared to be a defence of the prince, the Attorney, in a 10-page judgement, declared it was vital that Charles maintained a political neutrality - "a cornerstone of the UK's constitutional framework". He added that any suggestion Charles "was disagreeing with government policy would be seriously damaging to his role as future monarch."

These apparently measured words - Grieve, after all, had to tread carefully in overturning the ruling of three Appeal Court judges who allowed publication of the letters to seven separate government departments - fooled nobody in Whitehall or at Buckingham Palace and Clarence House.

They were a warning shot from the government's most senior law officer to the heir to the throne - that he had grossly exploited the hospitality afforded him by successive administrations, and that such behaviour must stop if he is not to risk his future position as King.

This, from a politician, is brave stuff. Those of us who have witnessed at close quarters the interface between MPs and the Prince are all too familiar with politicians' generally lickspittle approach when it comes to royalty. The most senior figures are just as vulnerable to a kind word, a warm handshake, and a personal invitation as are the new kids on Westminster's block. It is a human frailty the prince and his advisors have come to recognise, and to exploit quite ruthlessly. And who can blame him.

Indeed his supporters could probably produce evidence that it was the politicians themselves who invited Charles to cross the line from constitutional propriety to institutional interference - so why should he now be subjected to such unwelcome scrutiny?

Few will deny that over the past decade many of Charles's outspoken views have found a resonance, at the time or later, with pockets of the population. GM crops, urban blight, the foxhunting ban, the plight of the Dalai Lama - many of these soft topics found a resting-place in the royal pigeon-hole. Sooner or later there would be a defiant explosion, usually coupled with an emotional rider - "I might as well leave the country".

He's entitled, of course, to his view. He's also a useful rallying-point for those who find themselves disenfranchised or dispossessed - and our society is not so perfect that there aren't a few of those around - but the truth is that, constitutionally, the prince has no greater claim to preferential treatment from ministers than any single individual whose vote put the ministers there in the first place.

Much hot air has been generated in defence of the prince's need to inform himself of the machinery of government. Indeed, the main excuse the Attorney General offers for suppressing publication of Charles's badgering missives is that he was 'educating' himself about the work of government in preparation for his kingship.

Two points are worth making here. The Queen, whose 60-year reign remains unblemished, never once lobbied a minister during the years in the run-up to her ascending the throne. She was 'educated' well enough by courtiers and senior political figures of the day, but saw no reason to play a part in a process which she saw as the realm of politicians.

Second, the nearest example one can find of the exhaustingly long wait in the wings Prince Charles has had to endure is that of a previous Prince of Wales, latterly King Edward VII. During his 59-year apprenticeship for the throne, the prince was denied access to Cabinet papers by Queen Victoria; yet somehow it did nothing to harm to his short but successful sovereignty.

With this in mind the Guardian newspaper feels, quite rightly, that it's improper in a more egalitarian age for an heir to the throne to seek to influence the political process.
You have only to look to the example of another Prince of Wales, subsequently King Edward VIII, and his 'something must be done' remarks on the plight of the Welsh miners in the 1930s to see their point. Nothing was done - save bolster the prince's reputation as a man of the people. This couldn't, surely, be Charles's motive too?

And here lies the danger. Successive political administrations strive their best to make Britain a better place - sometimes they get it right, often they get it wrong - but they are bound by a political and constitutional convention which means that if public confidence in them fails, they go.

The same cannot be said of the Prince of Wales, who's there for life and answerable to nobody. Thus, if ministers are weak and allow themselves to buckle to his opinions - they are, and they do - they will inevitably allow the prince to ride roughshod over fundamentals established in Magna Carta, a document whose hard-won liberties have served the nation pretty well for 800 years.

This week the Prince's supporters came out with guns blazing, insisting he will continue to fight for causes he believes in even when he becomes King. This is an act of surprising folly, given the dressing-down he has just received from a senior government minister. It implies an arrogance and a lack of judgement which could yet see his undoing.

It is Charles's tragedy that his undoubted skills have been wasted over the years. But his impatience - at having to wait for destiny to come knocking - has spilled over into interference.

In Prince William, the nation sees a willing and able player of the royal game - charming and compliant, not overbearing and headstrong. The years are not being kind to his father, whose demands to be heard seem to grow exponentially.

Without a fundamental change to this damaging mindset Charles may find that those who believe, like him, that he must succeed his mother for the fabric of royalty in this country to remain untorn, may come to see things another way.