I'm sure all 60,000 people already knew how loathsome the BNP policies are, but there's nothing like seeing someone speak live, in the flesh, for heightening those emotions and provoking a response.
Seeing Griffin being put on the spot by David Dimbleby and having to think up an instant defence of his record, seeing him shake and smirk, was revealing and invaluable.
Griffin's TV appearance probably won't have lost him any existing supporters - and might just have found him a few extra ones - but it will undoubtedly have stiffened the resolve of all decent UK citizens to exercise their vote to keep the BNP out of all future elections.
When Obama won the US elections, I wrote here about how his massive and deserved following - fed by live rallies and TV appearances - had been extended skilfully online, but that the campaign still left me feeling a bit uncomfortable.
Hitler silenced media opposition through violence, but politicians can now create disintermediated relationships with their voting public, using uncritical films and adulatory prose on websites, away from the scrutiny of professional journalists. Speaking personally, I don't want that to happen - I value that critical filter.
Since Obama's victory, there have been countless instances where professional journalism has proved its worth: The Daily Telegraph bringing MPs' expenses into the light, The Guardian's pursuit of the Trafigura scandal, Channel 4's Britain's Forgotten Children season and Sky's commitment to taking us to the frontline in Afghanistan through news and documentaries.
But professional journalists don't always get it right. Witness Jan Moir's unpleasant nudge-winking comments about Stephen Gately's death in the Daily Mail. Public disapproval was swift: 22,000 complaints were registered with the Press Complaints Commission - an historic high - and online objections were copious, spontaneous and heartfelt. There were some accusations that the online campaigns were orchestrated, but that theory appears to be unfounded.
What fascinates me is how these two forces - professional journalism and citizens' voices - can work together to enhance democracy. Either one without the other would be less valuable.
We want neither uninformed online mob rule nor arrogant, unaccountable media organisations. While far from perfect, this balance seems to be keeping us all honest.