Sorry Dassie, but I'm still not following your argument. If there is a silent majority of people supporting the BNP, why do the BNP lose their deposit in virtually every election?
It's a secret ballot after all and the public are under no obligation to tell anyone who they have voted for, so Joe Public could say they, 'We're voting Conservative!' and secretly vote BNP, but they don't, do they?
I would therefore conclude there is an angry minority who support the BNP, but certainly no majority, be it silent or otherwise.