Man Widdecombe has a clip of a BNP interview on Radio 2 which demonstrates exactly why "no platforming" the BNP is a bad idea if you want to curtail their influence. They aren't evil geniuses who will convert people en masse to racism unless they are prevented from speaking, they aren't going to impress sceptical people with their honesty and plain speaking either. They are in fact evasive and blustering in a way in which spokesmen from normal minor parties aren't.
Which is why it is not the end of the world that Nick Griffin is going to appear on Question Time next week. If the programme goes ahead and isn't disrupted by protesters there aren't suddenly going to be hordes of brownshirts marching through Bradford. The other panellists which probe him on the BNPs views on race and Griffin will either have to answer it or avoid it, neither of which will show him in a good light.
The calls for boycotting or silencing the BNP carry the underlying assumption that the BNP are correct in their opinion that they represent a silent majority of the British people and it isn't a huge surprise that the most prominent supporters of the No Platform movement tend to be slippery figures like Denis Macshane and Peter Hain.