I don’t think a BNP to Tory switch is credible — even in the Tory sweep and winning only a single seat, UKIP took third place in total votes cast — and I think if polls confirm my analysis it will be a shame because it will make it easier for the main parties to portray UKIP in an unfavorable light, but I still suspect that’s what happened to the BNP vote.
I agree with your analysis.