A debate on Israel at the Oxford Union took place on Tuesday without any of the scheduled speakers, after a row over the make-up of the panel.
Three of the academic community's most vocal critics of Israel — Israelis Avi Shlaim and Ilan Pappe, and Palestinian writer Ghada Karmi — were due to propose the motion: "This House believes that one state is the only solution to the Israel-Palestine conflict."
But members of the Jewish community, including Harvard professor Alan Dershowitz and Peace Now UK co-chair Paul Usiskin, complained to the Union that it had given the anti-Israel side a "fourth voice" by having US political scientist Norman Finkelstein in the pro-Israel team, which also comprised Peter Tatchell and Northern Irish politician Lord Trimble.
Dr Finkelstein, who recently lost tenure at Chicago's De Paul University in a row over his views on the Holocaust, is "an extreme left-wing opponent of Israel" and provided a "covert ally" for the anti-Israel side, claimed Mr Usiskin.
Union president Luke Tryll withdrew the invitation to Dr Finkelstein, conceding that, with his presence "the debate would not be fair". He asked Mr Usiskin to stand in.
Dr Finkelstein said that the union had "shamefully capitulated" to the "bullying tactics" of Prof Dershowitz who, he claimed, is "determined to hound me out of public life". Mr Tatchell then pulled out over the Finkelstein issue, saying: "I don't agree with Norman on some things but I know of nothing he has said to justify his invitation being withdrawn.
"The attempt to ban him goes against the principles of free speech that the Oxford Union claims to defend."
Lord Trimble also withdrew, due to "diary pressure".
Dr Shlaim, who was due to speak against Dr Finkelstein, wrote to Mr Tryll saying: "Disinviting a speaker raises questions about the Oxford Union's commitment to free speech. Unless the invitation to Norman Finkelstein is renewed, I will not take part."
He and the others then pulled out, leaving just Mr Usiskin to debate with five union members. Mr Usiskin, who won the debate 191 votes to 60, said he believed they acted because their chances of winning were weakened.