Once in my life I stood a few feet from Princess Diana, and, though I was looking for her and knew she was there, and had seen ten thousand pictures of her, and watched her, shimmering, on many a TV screen, I did not recognise her. Eventually, on that gloomy winter morning in the forecourt of the Brazilian ambassador’s residence in Washington DC, I realised that I was almost within touching distance of the most famous woman in the world.

But she simply did not look like herself. If what I saw on that cold morning had been what the public were used to, her reputation and effect on the world might have been completely different. She looked a good deal more like the formidable natural politician she was, and a good deal less like the breathtakingly pretty but rather lost and lonely young woman most people thought she was. But the camera loved her so much that the world saw the naïve and lovely victim, not the brilliant wielder of public relations skills and tactical genius.

And I have been fascinated by that fact ever since. The woman I stood a few feet from was darker, sharper more serious and more angular than the wholly different princess I had seen many times in photographs or on TV.

Now, I know that the camera lies, or can be made to lie. I am not especially vain of my appearance (it would be futile, and seeing yourself many times on film rather cures you of any illusions) but I am sometimes astonished at the way TV cameras make me appear. When I occasionally catch sight of myself on cheap security CCTV screens, I usually find the image is closer to what I think I look like than the version provided by expensive BBC equipment, which is odd. Though I was amazed, a few years ago, by the difference (about two stone less, several fewer chins, and no view up the nostrils) when I appeared on a programme from the BBC’s Glasgow studios. After I had watched the recording, I actually rang up and asked if they used a different type of camera in Glasgow. Apparently not. Must have been something else.

So I am fascinated by these unquantifiable things. Do cameras see an essence that the eye doesn’t see, or do they miss important truths that the eye *does* see? And what did they see, or not see, about Diana?

As we ramble through the Diana saga yet again, I seem to recall a certain reluctance on my then newspaper to let commentators such as me say very much about it. Given the tendency to blame the whole thing on the media pursuit of the Princess (an accusation I rather resist), I think editors thought that commentators who were defenders of traditional monarchy might be best employed walking up and down the Pennine Way for a couple of weeks, with their phones switched off. Or something like that.

In retrospect, I am quite glad. One forgets at these times that very famous people are still people, who have families, and children. And when, later, one remembers, the damage is done. In Diana’s case, the dreadful circumstances of the two boys now seem quite unbearable to me. At the time, I might have thought that was something Diana might have thought of before she went off on Mr Fayed’s yacht. I now realise that makes no difference at all. The two boys transformed everything. They still do. They always will. When the succession comes, as come it must whether we want it to or not, they will transform that too, nobody knows yet exactly how.

Alastair Campbell, another propaganda genius, realised the power of Diana’s sudden death immediately and instinctively. He can probably sort of explain it now, but the thing about such people is that they just know, at the time, exactly what really matters. I have no doubt that the phrase ‘the People’s Princess’ was his invention, not the Blair creature’s. Alastair is of course a lefty and republican by instinct, but he had far too much strategic sense to make a frontal attack on the Monarchy in 1997.

What he could do and did was to inflict a huge defeat on old-fashioned monarchists who had identified the monarchy with tradition, heredity, Christian marriage and the Protestant settlement. He stole the monarchy from them, and they have no idea how to get it back.

Not that they had done much to defend it. British conservatives had not understood the nature of the challenge to them. Nor did they believe in anything sold enough to provide a basis for resistance. Even now, they have failed to realise that you cannot fight an ideological enemy, such as the cultural revolution is, unless you understand it and have a counter-argument of your own.

They had just assumed everything would survive. The Royal Family itself, oddly enough, had not assumed this. Very much on their own, they have long realised that those who appear to be their political or media friends can vanish at any time, and they need to think constantly about how to survive. Alas, their ideas are not very good. ‘It’s a Royal Knockout; was perhaps the worst of all. But there were other mistakes. Sensing, in the late 1960s, that it needed to become more ‘relevant’, the monarchy permitted a BBC ‘fly-on-the-wall’ documentary, in which cameras and microphones were allowed rather close to Majesty. The programme, broadcast in 1969, was a disaster. It has never been shown in full since, and no wonder.

Monarchy itself may be a great shining castle of lofty ideas, perched atop a mountain of loyalty and history. But its individual members are just as banal and uninspiring as anyone else. And once this gets abroad, the whole thing loses its power, which always existed in the imagination.

Television eats the imagination, as zombies hunger for the brains of the living. The more you watch, the less you can imagine, the harder it is to believe in anything you cannot see on the screen, and the easier it is to believe anything you can see on the screen.

Diana, the beautiful, lonely betrayed star, intense and full of wounded feelings, star and director of her own beautiful tragedy, shone on the screen like gold and diamonds. She swam in the jewel-like lights of the TV cameras (which have beguiled many, but which she beguiled) .The old royal family, unless they were actually in the trappings of gold coaches, crowns and sceptres, just looked like an episode of Crossroads with slightly less wobbly sets.

And when this drama series moved on from her astounding TV interview, and became genuine tragedy in Paris, there was nothing that could compete with it. All that was left was to find a way of giving in to it.

Since Diana’s funeral, the monarchy has embraced political correctness and the new thinking, and made it pretty plain to social conservatives that it does not want to be recruited to their cause, and won’t help them if they call on it. That was Alastair Campbell’s achievement. One of the great forces of conservatism had been swallowed up in the New Labour project. It wasn’t the only one.

Of course the Queen’s sister and her children had already had their marital troubles. But they tended to be six of one, half a dozen of the other problems in which nobody had ever invited the public to take sides. It is impossible even to imagine the Princess Royal giving a TV interview about her marital life. But Diana the Beautiful was a symbol, to many, many women who had been, or thought they had been, betrayed by their menfolk. And when something happened to her, a lot of these women thought it was an establishment revenge of some kind; or they thought it was a jolly good opportunity to blow raspberries and make rude gestures in the general direction of Buckingham Palace.

Hence the strange applause for Earl Spencer’s remarkable funeral oration. It wasn’t that they liked the Earl, or thought all that much of his rather odd remarks about the ‘Blood Family’. It was that they enjoyed watching somebody doing down the Palace, and the blokes, and the toffs. They enjoyed this even if, perhaps especially because the person doing this was a bloke, and a toff, and lived in a big house. As so often, it’s what you are *against* that counts.

It wasn’t just the Great Legion of Wronged Women which No Man can Number, who took this view. Diana had another wider constituency as well. This was thanks to her interesting and quite correct literal embrace of HIV sufferers. This was an action of undoubted goodness and kindness, which I applaud. But it had a bigger significance too.

It had been the Thatcher government, by its odd reticence about the true nature of HIV transmission, which had created the ridiculous impression that AIDS was a contagious disease which could be communicated at a touch. Some of you may remember the curious ‘Don’t Die of Ignorance’ campaign which in my view spread a huge amount of ignorance by suggesting incorrectly that everyone in the country was equally at risk.

But that wasn’t how the social and sexual liberals saw her action. They saw it as a Royal embrace of the sexual counterculture, and a Royal snub to social conservatism and traditional morality. They may well have been right to do so, given Diana’s subsequent actions. Whether they were right or not, Diana then became beloved as a rebel against the establishment by many other groups of outsiders. Not since Edward VIII and his ‘something must be done’ had there been such a subversive at court.

But Edward VIII did not have television, or the subtle anti-monarchism of the Murdoch press, on his side. In the end, the great media magnates of his time were persuaded to support the establishment.

There is another point about this. We shall never know exactly how Prince Charles came to marry Diana Spencer, who urged it on, who opposed it, what went through their heads. But it is at last tempting to believe that there were voices who felt there was something ‘go-ahead’ as they used to say, something ‘progressive’ and ‘modern’ about bringing this young woman into the heart of monarchy.

How right those voices were. Modernity was what they got, by the trainload. And a fat lot of good it has done them. Try as I may, I cannot see the monarchy surviving very long after the present reign. As in all those fairy stories where three wishes are granted, it is very often terrible to get what you want.

Mind you, did the poor old monarchy have much life left in it anyway? The country of 1689, the year in which our ingenious form of government was devised, which made us the wealthy stable, powerful, free and independent nation we used to be, suffered a fatal stroke around about 1914, and has been an unconscionable time actually dying, ever since.

But it is dying, and it is as able to sustain a constitutional monarchy as it is able to sustain a cold-war nuclear deterrent. Technically, it has it, but it can’t maintain it, isn’t big and strong enough to keep it in working order, but from a distance it still looks OK, and it can’t quite bring itself to admit the truth yet. I must get back to writing my obituary of the country formerly known as Great Britain.