Oxford Union, Fascists and Free Speech?

A story in The Independent (Monday 19 November 2007 pg 5) about a controversy at the Oxford Union revolving around a upcoming debate entitled'A Night of Discussion on the Limits of Free Speech' caught my attention and to some degree disturbed me. A number of high profile guests, including The Defense Secretary Des Browne, Labour MP's Chris Bryant and Austen Mitchell as well TV presenter June Sarprong, have cancelled there appearances in protest to inclusion of Nick Griffin (leader of the BNP) and the well known Holocaust denying historian David Irvin on the speakers list.
Now I can see why sharing a building let alone a podium with Nick Griffin would not be a pleasant experience. (My knowledge of of David Irvin is limited to his Holocaust denial and histories of rather dubious merit. However the from the little research I have done he seems to be very much of the same nasty ilk of Nick Griffin, with an academic veneer). However what I do not understand that attitude of these labour MPs. They are not being asked to speak at a BNP rally but instead are being asked to discuss freedom of speech. Surely one of the central tenets of the principle of freedom of speech is that we allow both the speech with which we agree and the views which we find morally reprehensible. Events like the above offer the perfect opportunity to argue against these racist and anti-Semitic views. Simply banning or ignoring views we disagree with or find evil will not result in their disappearing or becoming less prevalent, the only way for this to happen is to debate the issues openly and show the stupidity of both the views and those the hold them.
This banning of views and opinions that are clearly intolerant is a worrying trend for the Labour government, which has made a habit of criminalising speech likely to incite hatreds of various types, while at the same time banning certain rights of protests. Maybe this is simply a continuation long held paternalistic attitudes of the Labour party, the current government certainly gives the impression of not trusting the judgement of the people.
To me one of the the things that makes Britain, Britain and one of the things that makes me proud to be British is our long history of freedom of speech and accepting dissension. Despite or maybe because of this tolerance and all views and peoples Britain did not fall pray to any of the forms of extremism of the last century. One can only hope that this new found enthusiasm for banning and refusing to intelligently refute the intolerant views of others does not open our society to the very forms of extremism we are hoping to defend against.