The last couple of days in New York have provided a chance to compare the styles of two presidents and a nearly-president. On Tuesday George W Bush spoke to the UN. On Wednesday, a few blocks from the UN, Bill Clinton opened his 2007 Clinton Global Initiative. And – in the opening session – he shared a platform with Al Gore. Rather to my surprise, I thought the famously wooden Gore gave the most impressive and charismatic performance of the three men – aided by the fact that the opening session of the CGI focused heavily on his special subject: climate change.

Relations betweeen the Gore and Clinton camps have been tense since 2000 when, in the aftermath of the Lewinsky scandal, Gore’s presidential campaign deliberately tried to put some distance between him and Clinton. But in the opening CGI session, the two men seemed to get on fine. In fact, I rather longed for Gore to disrupt the sugary sweetness of the occasion by making a shock announcement that he will run for the presidency against Hillary. That would have put Bill on the spot.

Clinton’s presentation was a reminder of his formidable ability to combine personal charm, with a nerdy command of policy detail and relentless optimism. He still favours argument by anecdote. Clinton’s favourite rhetorical technique is to outline some huge policy problem, and then point to a local example – preferably combined with an uplifting personal story – that points the way forward and shows that all problems are soluble. In the opening panel, Clinton used Lee Scott – the boss of Walmart, who was also on the platform – as a sort of prop.

Tuesday was the big day at the UN General Assembly. Global leaders rushed to the podium, one after the other. We had the heads of government of South Africa, Indonesia, Germany and many others. But it was clear who the big three were – Bush, Sarkozy and Ahmadinejad. Bush because of his job, Sarko because he is still a novelty – and ADJ because he says outrageous things and is at the centre of a gathering international crisis.

It was fascinating to sit through an entire Ahmadinejad speech and press conference for the first time. I thought he pulled off the difficult trick of being simultaneously boring and sinister. Boring because he goes on and on about religion. I don’t know why this surprised me – it is the Islamic Republic of Iran, after all. But the religious rhetoric is usually wisely edited out of the compressed version of his remarks. Having to listen to it all in full, is a bit like being trapped on the doorstep by a Jehovah’s Witness. On the other hand, I also found his performance sinister because it is clear that he is genuinely obsessed by Israel. These are not stray remarks, forced out of him. He can’t keep off the subject.

This is the big week at the UN General Assembly. But it’s already clear who the star of the show will be – Mahmoud Ahmadi-Nejad, the president of Iran. Ahmadi-Nejad is often portrayed as a dangerous simpleton. But he has played the PR game with masterful precision, since his arrival in New York.

Today (it’s still Monday night in New York), he limbered up for his appearance at the UN General Assembly by talking to an audience at Columbia University, in upper Manhattan. He was greeted with screaming headlines. The New York Daily News splash was "The Evil Has Landed" – with a sub-title -"Hate spewing Iran prez speaks today at Columbia.". For good measure, the paper ran an editorial accusing Columbia of "Monstrous Idiocy". Perhaps intimidated by all this pre-publicity, Columbia’s president – Lee Bollinger, (a champagne socialist?) – spoke for 10 minutes before the Iranian president and accused him of being a "petty and cruel dictator." This played into Ahmadi-Nejad’s hands. He mildly rebuked his host for being discourteous – and smilingly dodged all difficult questions about Israel or the Holocaust. The only moment when he appeared genuinely ridiculous was when he denied the existence of homosexuality in Iran.

Earlier this year I got an e-mail from a reader accusing me of combining the “worst qualities” of Adolf Hitler and Neville Chamberlain. My offence had been to write a column suggesting that it would be a bad idea to bomb Iran’s nuclear facilities. This, apparently, meant that I was in favour of the annihilation of Israel (hence Hitler) – and also that I was a pathetic coward (Chamberlain).

This kind of rhetoric is not unusual. As I write, Columbia University in New York is being accused on television of “hosting Hitler”, because it has invited President Mahmoud Ahmadi-Nejad of Iran to speak on campus.

Personally, I found being compared to Chamberlain particularly offensive. There are few more damaging taunts than to be compared to the British prime minister who tried and failed to appease Hitler at the Munich summit of 1938. In the US, in particular, the ghost of Chamberlain is regularly brought out to frighten those who are deemed insufficiently resolute in confronting the enemy of the moment. In the run-up to the Iraq war, the lessons of Munich were invoked by President George W. Bush and any number of neo-conservative commentators.

Ileana Ros-Lehtinen, a Republican, was at it again during this month’s congressional hearings on Iraq. She reminded her audience that: “Neville Chamberlain genuinely believed that he had brought ‘peace in our time’ by washing his hands of what he believed to be an isolated dispute in ‘a far away country between people of whom we know nothing’. That country was Czechoslovakia and Chamberlain’s well-intentioned efforts … only ensured that an immensely larger threat was thereby unleashed.” The lesson was clear. Confront evil regimes as soon as possible.

The remainder of this week’s column can be read here (FT.com subscribers only). Comments can be made below.

I was sorry to read today that Joseph "Erap" Estrada, the former president of the Phillippines, has been sentenced to life imprisonment for corruption. I have a soft spot for Erap. He is the only politician I have ever interviewed who actually fell asleep during the interview.

It was in the mid-1990s and Estrada was vice-president at the time. He was also enormously popular with the poor in the Phillippines – largely because he had played a series of heroic roles in low-budget thrillers. He was clearly the coming man, so getting an interview with him was quite a big deal. He had a large office, full of note-taking flunkies. They were as horrified as I was, when the great man nodded off and began to snore during the course of our interview. But I can’t really blame him. It was hot; I was asking a lot of damn fool questions about development and foreign policy. He might have had a few at lunch. He has a reputation as a world-class drinker and womaniser. Eventually I was ushered to the door by a staff member who said:  "I’m sorry about that, but I could tell the vice-president was very interested by your questions until he fell asleep."