I don't think idiotic protestors increased the interest in people joining his party. Yes, they were idiots but I think we have to realise that the people who do support him, support his policies, his racist ideals and his attitudes towards other minority groups. People like him, people respect him and his ideas. The majority of people who support him, I'd guess, are like him - peas in a pod. If someone is racist, it wasn't last nights demonstrators that made them racist, they were racist already.
NG himself is a minority group because there will never in this country be majority (or anywhere near) support for him. If having been on Question Time allows these people to feel able to join his party of whatever, let them. Not my business.
He might boast of support increasing or whatever, that means nothing. It means nothing because his numbers will never be enough to make a difference that matters.
Last night was always going to be about NG and the BNP. People wanted to pin him down, ridicule him and quite frankly it is what he deserved. He can play victim all he likes, it will make not a jot of a difference to people who do not support him. He can complain all he likes because he will never be able to implement his policies in our country and that fact is the trump card.