It's a tricky balance. My first instinct is to say ignore them and don't give them oxygen but then if they are genuinely seen as a threat ignoring them could be a bad move. I certainly think they should be kept an eye on but I really think having government statements and news stories about them...
Whatever I think about leave voters I don't think they are national socialists and I sincerely believe most people in Britain would steer well clear of this group without a ban. In fact I think banning them is the wrong move.