But the biggest difference between then and now, of course, is that we marched against our government when it supported dictators, not when it removed them. The logic of the anti-Vietnam War movement was that America, in its ferocious determination to hold back the spread of communism, was prepared to back the tyrannical Diem regime in South Vietnam even to the extent of thwarting democratic elections when they threatened to put communists into power.

Our complaint was that America's foreign policy was deeply hypocritical and self-serving: committed unswervingly to democracy and liberty at home, while supporting any murderous despot abroad who was prepared to be "our son of a bitch" rather than the other side's. The ultimate paradox is that the country that still behaves in this way - prepared to do business with pretty much any murderous regime or criminal dictator who will cater to its interests - is France: the nation that today's anti-war protesters regard as the epitome of wisdom and restraint.

But the "warmonger" Bush, supported by the "liar" Blair, is doing precisely the opposite in Iraq, where a peculiarly vicious tyrant has been overthrown and subsequently arrested with due legal process, in the hope - idealistic and even naïve, perhaps, but unquestionably sincere - of introducing democracy and freedom to his country.

I watched Michael Moore's buffoon-ish reaction when he was attacked by John McCain at the Republican convention, over and over again yesterday.

Fox News showed it repeatedly, probably figuring that the sight of Moore behaving like a snotty 10-year-old defying the headmaster was the best gift the anti-war movement had presented to George W Bush since Howard Dean's "I Have a Scream" speech. (The BBC, which also ran it time after time, was presumably just overcome with admiration.)

And as I watched this puerile performance from a man who is regarded as the spiritual leader of American, and now British, conscientious protest, I thought "Has it come to this?" Is this how it ends, the great modern tradition of American dissidence launched by my generation of students in the 1960s?