Protesters said they were pleased to have made their point.
EXTREMISM
Commentators had lined up to condemn the union for staging the debate, saying the student-led organisation was giving a platform to extremism partly in an effort to attract attention. The union has previously invited Kermit the Frog to speak.
Enraged at Irving's invitation, several prominent people, including British Defence Secretary Des Browne, cancelled engagements for future debates. A politician from the opposition Conservative Party resigned from life membership of the union.
Irving, 69, has written several books which defend Adolf Hitler and deny the systematic extermination of six million Jews by the Nazis. He has been branded anti-Semitic and a racist by a British judge.
Griffin's party is on the fringe of British politics, earning a reputation for strident positions against Muslims and immigration, although he has denied racism.
Oxford Union President Luke Tryl had defended the decision to invite the two saying the best way to counter extremism was to defeat it intellectually in debate.
"These people are not being given a platform to extol their views but are coming to talk about the limits of free speech," he wrote in a letter to union members who had expressed concern.
"It is my belief that pushing the views of these people underground achieves nothing ... Stopping them speaking only allows them to become free speech martyrs."
Ned Temko, chief political correspondent of the Observer newspaper and a former editor of the Jewish Chronicle, said it was disingenuous of the debating society to invite the two and then try to hide behind the banner of freedom of speech.
"It's not a question about giving them a platform, it's about giving them credibility," he told the BBC. "It's ridiculous and it's irresponsible."
