Tough issue
for me the BBC have got it right, the BNP has slowly grown without the main tv channels involving them, a growth fuelled by ignorance of what they really stand for.
imo the best way to counter that ignorance is by getting the BNP out of the shadows into the spotlight and make them , by debate, expose the flaws in their policy.
The other political parties however need to address peoples fears regarding immigration by enforcing laws that already exist with respect to Illegal immigration and unfair, or perceived as unfair, practices in housing etc