So, if you were a non-white member of the general public, would you be happy about members of the BNP being Police officers...or do you think that they could separate their duty to uphold the law from their political offiliation, and not allow one to interefere with the other in their dealings with you?
Offically they have to seperate their duty from any political offiliation regardless of what colour that might take. How practical that is remains to be proven BUT if you ban the police from joining the BNP then they should be banned from joining Labour, the Tories and any other party.