Is there an easier to person to poke fun at than Prince Charles?

From his earliest appearance on our front pages - who can forget his ordering of a cherry brandy in a pub while still in breeches at Gordonstoun? - he has added much gaiety to the nation and provided the tabloids with a steady drip of drivel, little of which has any kinship with truth. Of course, Charles himself is not without blame or shame. His justifiable antipathy towards the fourth estate has meant that his affairs are more opaque than transparent and, as he has aged and his voice has got even more plummy, he seems less like someone you might bump into while purchasing organic sausage rolls at the local deli and more like a wide-eyed visitor from another galaxy.

Catherine Mayer, Time magazine's editor-at-large, calls this strange place Planet Windsor, which features in the sub-title of the American edition of Charles: The Heart Of A King. As befits someone schooled in a more rigorous journalistic environment, she is scornful of those of my colleagues who, in the absence of verifiable fact, resort to invention, distortion and, in the case of the much-unlamented News Of The World, skulduggery.

At the outset, she gives as an example of this the oft-repeated story that Charles insists his staff boil seven eggs in the hope that one will prove to be of the right breakfasting consistency. No less an authority on royal mores than Jeremy Paxman went out of his way to get to the bottom of this alleged scandal and came to the conclusion that it "seems so preposterously extravagant as to be unbelievable". Mayer, however, is made of less gullible stuff and thinks there may be more to it than meets the eye. Suffice it to say that numerous eggs may indeed have been boiled but Prince Charles, who abhors waste, probably did not issue an edict to that effect.

It is a trivial matter but it is indicative of the manner in which one can be diverted when dealing with the prince of Planet Windsor. Mayer is at pains to point out that hers is not an authorised biography, nor, I would suggest, is it really a biography. Rather it is a series of essays which look into different periods and aspects of Charles's life and obsessions.

Mayer was invited to various functions and attended others in her role at Time. She met a number of Charles's friends, few of whom have much to say beyond platitudes and compliments. For example, one sycophant - apropos the need for toilet breaks - told her: "He knows exactly how to hydrate his body to just the right degree. It's an incredible talent." Which I dare say it is. She was also granted a half hour interview with the prince, during which nothing of personal substance appears to have been discussed. In that regard, she had much less access than, say, Jonathan Dimbleby, on whose book Mayer draws from time to time.

It is inevitable, therefore, that much familiar ground is covered and little is added to the sum of our knowledge about a man who to all but his nearest and dearest remains an enigma. What does distinguish Mayer's book from many others on the same subject is its intelligence, wit and compassion. She is not uncritical of Charles - she is republican after all - but she is sympathetic to him and tries hard to understand him. What emerges is a portrait of a well-meaning fellow, a serial founder of charities and pursuer of good causes, who at times may appear like a pub bore and Luddite and at others lonely, melancholy, misunderstood and frustrated.

He is undoubtedly sincere, for instance, in his ambition to save the world and improve the lot of countless of its inhabitants. To this end, he knows that he can put people together in rooms who would otherwise never meet, and he has no qualms about asking the rich and powerful and possibly dodgy - known on Planet Windsor as "Bond villains" - to dip into their pockets and fund his pet projects, including Dumfries House and the adjacent model village of Knockroon. Moreover, he is not, Mayer insists, obsessed with ousting his mother for that would surely curtail his ability to speak out, as he did earlier this week when addressing the radicalisation of young British Muslims.

The prince that emerges from the darkness is very much a product of his weird upbringing. In the absence of a father's shoulder to cry on - Philip's upper lip is stiffer than even those made by plastic surgeons - he sought succour from Lord Mountbatten (who was as much of a matchmaker as one of Jane Austen's characters), Laurens van der Post and even Jimmy Savile. Among his women friends there is Emma Thompson who does her best to make him laugh and cheer him up. She seems sane, if that can be said of a luvvie.

Around women Charles was inevitably gauche. Mountbatten encouraged him to sow wild oats but how is that possible when your girlfriend is expected to address you as "Sir"? Before Diana came along the best candidate to give him an heir was Amanda Knatchbull, Mountbatten's grand-daughter, but she rejected him when he finally got around to asking her to marry. "She had seen enough of his life," writes Mayer, "to know what being Princess of Wales might entail."

What of Diana? Mayer does not fall into the trap of being partisan, preferring to see fault on both sides. Ill-matched and incompatible, she and Charles were thrown together after a five-month courtship and, before either of them knew it, the banns were published and a shindig arranged at St Paul's Cathedral, which could not be cancelled. Camilla was the woman Charles ought first to have married but she was not "intact". It is what Mayer terms "the inertia of tradition" on which the whole preposterous edifice of our hereditary monarchy depends for its survival.