Americans and others who may well be unfamiliar with the BNP (British National Party) should think in terms of your white supremacists and the Ku Klux Klan; that sort of thing, except that nowadays they keep the violence in the background and aspire to electoral success. They have won a few seats on Local Councils in the last year or two, trading on the build-up of racism in deprived communities.

I wouldn't think of it as 'free publicity'; these aren't naïve fans who think they are doing you some sort of favour by pirating your recordings. They are using you and others in an attempt to legitimise their cause. Allow the material to stay in place and you risk seeming to endorse that cause. Even if you don't care about copyright theft as such, there's more than just that to consider in this particular case.