Joan Smith: Good grief, man. Write into Home Truths and have done with it

Charles is still waiting for a job and it seems to be driving him mad

Why didn't he just send it to Radio 4's Home Truths? The programme revels in just the type of banal observations and failed attempts at irony that characterise the Prince of Wales's diary of his trip to Hong Kong in 1997. Whatever the outcome of his ill-judged action against a Sunday newspaper for breach of confidentiality and infringement of copyright, the proceedings confirm a growing perception that a man who is so weak and self-regarding, so childish and lacking in self-awareness, is simply not fit to be this country's next head of state.

At first sight, the latest revelations confirm previous insights into the Prince's infantile habits and cosseted lifestyle. Now we can all savour his Pooterish dismay at being denied the chance to fly first class to Hong Kong, in a diary entry which surely deserves to be set to music and performed by a chorus of puzzled upper-middle-class twits, ascending the steps of an aircraft and singing: "What is this thing called Club?"

Like almost everything the Prince has done, the consequences of his decision to take The Mail on Sunday to court have been the exact opposite of what he intended: publication of extracts from the "private" diary on a grand scale after other newspapers successfully petitioned the court for permission to see the material in full. It followed the pricelessly comic revelation, contained in the witness statement of the Prince's former deputy private secretary Mark Bolland that his former employer regards himself as a "dissident working against the prevailing political consensus".

For republicans, there is some compensation in the spectacle of hereditary monarchy self-destructing. As he approaches an age at which many people are able to look back on a career of solid achievement, the Prince is still waiting for a real job and it seems to be driving him mad. The latest insights into his character suggest someone verging on delusional; while enjoying massive privileges of rank and wealth, Charles persists in seeing himself as an outsider, battling against orthodoxy and standing up for his principles no matter what the cost to himself.

That he flouts those principles on a daily basis has not entered his head; this is a man who wants us to lead as green an existence as possible, but he jumps on planes as often as ordinary people take buses; he complains about the absence of democracy in China and Tibet but sucks up to the Saudi royal family, overlooking their scandalous human rights record; he poses as a champion of rural life, campaigning not for decent agricultural wages but ancient aristocratic pursuits.

The extent of his political interference has begun to emerge into the public gaze, sometimes to the quiet delight of ministers nagged by handwritten letters on just about every subject. It is all beyond parody, and commentators who defend Charles by saying he is entitled to express his views miss a crucial point. The Prince is a dyed-in-the-wool reactionary whose opinions are out of step with the anti-conservative consensus in modern Britain. If we had an elected head of state, his preposterous anti-scientific views would be balanced on other occasions by a different popular choice, but that option is not open to us.

What we have learnt from leaks and farcical court cases is that the heir to the throne knows his position requires him to stay out of politics, a convention he flouts. This is unsupportable in a modern democracy, which requires a head of state who regards their position as an honour, not a birthright to be casually and persistently abused.