Looks like the original BBC story - which they hastily pulled to replace with something more anodyne - was kosher.
Yorkshire Post and icHuddersfield also report that BNP members were the potential target of the two young men arrested under the Terrorism Act 2000.
We're in new territory here. I can't remember any previous cases in UK history of trying to kill people for their party membership, although one Billy Bragg did call in a Guardian interview for BNP members to be "duffed up in the street", while a Jeremy Hardy said on the BBC that they "should be shot in the back of the head".
UPDATE - when one considers the relatively peaceful past of UK party politics, one does tend to forget Erin's green isle, where killing politicians is an old and dishonourable tradition both North and South of the border - although even then, did people try to target ordinary members of, say, the DUP ? The situation is complicated when you consider that some parties were terrorist front organisations.
Which countries have traditions of political violence aimed at ordinary party members or supporters ? Well, pretty much all of them outside the Anglosphere and some parts of Europe, really. Pakistan and Bangladesh for starters. India's not immune. The Land of Wood and Water.
Looks like we're not just getting the voting practices of the subcontinent along with the kuthlama and the dosa.