TWENTY-FIVE years ago yesterday, thousands of demonstrators marched on London's Grosvenor Square to protest against the war in Vietnam. It was the iconic event of the British Sixties for the generation that was going to change the world. Power to the People] It was instant ideology you could pin on your sleeve, but better than no myth at all; everyone who was anyone came, including a student from Arkansas called Bill Clinton. As the North Vietnamese flags were unfurled against a blue March sky, kids in beads and beards eyeballed cops on horses and, without a hint of irony, everybody shouted 'Ho Ho Ho Chi Minh]'.

People got hurt at Grosvenor Square. At the intersection of absolute conviction and moral fervour, we were careless. But angry, expectant, as we planned to end the war and banish forever the time-servers and morally middle-aged. What I'm wondering as a result of wildly disparate things that have been in the news and on my mind - John Birt, Richard Nixon, middle age - is how in the hell did we get from there to here?

How did we get to be a generation of whining fortysomething time-servers, denizens of an era when no one says he's sorry, no one resigns, and any crook can be recycled if only he hangs around long enough? Bill Clinton has even invited Richard Nixon to the White House to advise on supporting democracy in Russia, a subject on which he has become sage-in-residence.

That Tricky Dicky is smart about Russia is undoubtedly true, but so what? I mean what if Saddam Hussein's excellent plan for street lighting surfaced? And what is Hillary Clinton going to say when he comes to dinner? 'Hiya, Dick. It's ages since I worked on the committee to impeach you . . .'

I remember exactly how the constraints of democracy at home always seemed to irritate Nixon, I remember that sallow face with its five o'clock shadow showing contempt for anyone who got in the way. For Nixon, all students were bums. Nixon was the demon of my generation.

In the autumn of 1968, after the assassinations of Martin Luther King and Bobby Kennedy, after French students went to the barricades and the Prague spring was crushed by Soviet tanks, Nixon was elected President on a law- and-order platform. Six years later, he resigned only when faced with impeachment. For some, given the secret war he ran in South-east Asia, he was an actual war criminal; for most, given Watergate, he was, at least, a crook. He never really thought he did anything wrong. More importantly, he never apologised.

John Birt, the BBC's embattled director-general, was a fully paid-up member of the generation of 1968, none more so given his moral rectitude and political correctness. Still, as he set out last night for the 'dinner from hell' to mark the departure of his predecessor, Sir Michael Checkland, he went more in the spirit of Nixon than Grosvenor Square.

I do not want to imply that John Birt in any way resembles Richard Nixon. I know and like the man. But his victorious finger-pointing PR men have stonewalled with rhetoric that is downright Nixonian: Mr Birt was the 'victim of a disaffected mob'. The press was 'guilty of journalistic invention'.

But then this is the age of sanctimonious denial: Nixon is canonised. Such ministers as David Mellor only resign if caught out; John Major never regrets anything. And Norman Lamont, without a hint of self-reproach, announces a Budget in which every Briton will be worse off because of the government screw-up of Black Wednesday.

You know what? Most of us aren't much better than Mr Birt or the rest. All over town, Mr Birt's opponents have charged up the moral high ground. A lot of people have suddenly whipped up a view not just about Mr Birt's taxes, but about the entire BBC. I know many people who work in television: all of them have known about its problems for years. Did we get up and shout about it? Did we hell] We were looking for the fattest deal, the shiniest golden handcuffs or, at best, sitting in complicit comfort on the fence.

Back in the days of Grosvenor Square - I don't care if this is naive and sentimental - we figured that when we grew up, we'd seize power and make the changes. Don't get angry, get even, in the brutal but useful words of Bobby Kennedy. We didn't, though. We've become what we could never imagine being: corruptible and unapologetic about it, and, saddest of all, middle-aged.