Other guests at the society denounced gays, Jews, women, Christians, Hindus and Muslims who freely decided to change their mind about their religion. One regular invitee, Abu Usama adh Dhahabee, was caught on camera by Channel 4 crying: "We ask Allah to bring about the means and the ways in which the Muslims will get the power and the honour of repelling the oppression of the kuffar, where we can go out and perform the jihad. We ask Allah to bring that time so we can be participants in that. No one loves the kuffar. No one loves the kuffar. Whether these kuffar are from the UK, or from the US...We love the people of Islam and we hate the people of the kufr. We hate the kuffars. Whoever changes his religion from al-Islam to anything else, kill him in the Islamic state. Do you practise homosexuality with men? Take that homosexual man and throw him off the mountain."

Naturally, I wanted to hear the liberal administrators of a college inspired by the anti-clerical ideals of Jeremy Bentham explain why they allowed the death cults of the most anti-liberal ideology on the planet to flourish in their university. Unfortunately, the debate organised by UCL's admirably lively students began with a disappointment. Malcolm Grant, the university's provost, had stuck his head above the parapet a few days earlier to condemn the "quite disturbing Islamophobia" the case had raised, but then he ducked for cover and refused to attend.

In his place, he sent Philippe Sands, a law lecturer who is always accusing Tony Blair of being a war criminal for overthrowing the Ba'athist regime George Galloway saluted, but appears undisturbed by the production of actual criminals by his university. He didn't want to spy or snoop on his students, Sands said, and didn't see why any reasonable person should expect him to. His contemptuous tone and languid manner suggested that only modern McCarthyites could disagree. Following him was Wes Streeting, the Labour president of the National Union of Students, a young politician so stunningly slippery a seat in the Cabinet surely awaits him sometime in the late 2020s.

Streeting is gay as well as being left-wing. But he showed no concern about the presence of lethal homophobia and anti-Semitism among NUS members or about the pressures on Muslim students to conform to the dictates of Islamists. Instead of confronting an enemy in plain view, he thundered that the real foe of liberalism was Douglas Murray, the director of the Centre of Social Cohesion, who was speaking on the other side of the debate. Murray was a racist and an Islamophobe, he declared, without a care for the laws of libel or rules of honest debate. It was Murray who needed deradicalising, not student Islamic societies. He carried on in this vein even though virtually every Muslim who took to the podium agreed with Murray rather than him.

In theory, Streeting and Sands had a respectable argument at their disposal. Far from being racist monsters, Murray and his Muslim allies were, if anything, politically correct. They insisted in a rather wet manner that the university had a "duty of care" towards its students. Its own rules obliged administrators to protect the young from extremist preachers, and dangerous ideas. I listened uncomfortably. I have never believed in "no platform" for racist policies as long as liberals are at hand to confront racists and demonstrate to onlookers the malice of their arguments. John Stuart Mill, Jeremy Bentham's intellectual successor, opposed censorship but supported censuring. He wrote in his classic assertion of the need for free speech On Liberty:

"The peculiar evil of silencing the expression of an opinion is that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error."