"The case against inviting the BNP to appear on Question Time is a case for censorship..."

"... the case, in other words, that (in the opinion of those who make it) the BNP's policies are so abhorrent and so liable to sow hatred and division that they should be excluded from this form of public discourse altogether.... [I]t is unreasonable and inconsistent to take the position that a party like the BNP is acceptable enough for the public to vote for, but not acceptable enough to appear on democratic platforms such as Question Time. If there is a case for censorship, it should be debated and decided in parliament."

A hot debate in the UK. 

More here.