I think it does.
To my shame, I forget what this effect is called (anyone?), but there’s a phenomenon in psychology that influences how people choose between options.
Say you give people a choice of wines (they’re not paying): vintage red or vintage white. They might divide 50-50, let’s say. But if you offer a choice between vintage red, bog-standard white and vintage white, something funny happens. Unsurprisingly, nobody picks the bog-standard white, but the balance between vintage red and vintage white shifts significantly in favour of the latter: 40-60, perhaps.
Why? Well, within those three options, there’s an immediate and easy comparison between two of them: the vintage white and the bog-standard white are the most similar pair of the three, clearly the same sort of thing – and one is obviously superior. This comparison, though, serves to boost its standing across the board, and so while it might in a one-or-the-other choice be on a par with the vintage red, in this case its first-round win (so to speak) gives it the momentum to score a clear victory in the final.
It’s as if the choice of ‘good red/bad white/good white’ is understood as ‘good red/worse white/better white’: ‘better’ beats ‘worse’ but ‘better’ also beats ‘good’.
So: to the BNP, who will be delighted to play the role of the bog-standard white.
Given a choice between the mainstream parties and UKIP, people might split 90-10 (purely illustrative numbers). A choice between the mainstream parties and the BNP might result in 95-5. But, in a choice between the mainstream parties, UKIP and the BNP, you might get something like 77-20-3.
What’s going on is this: with the options of both a thuggish, overtly racist nationalist party and a more middle-class, somewhat xenophobic nationalist party, there will still be some who prefer the racists. But the more genteel nationalists could actually increase their vote as a result of the BNP presence, because by contrast they are the more acceptable face of nationalism. Those voters leaning in that direction will be more tempted by the ‘better nationalists’. The BNP, rather than taking votes away from UKIP, could actually boost them by making them look more moderate and desirable.
And in this case there’s an added dynamic: a fair bit of energy from the main parties (and other groups) is – rightly - going into attacking the BNP for being dangerous extremists; this effort diverts them from attacking UKIP.
It’s a bit like the sort of triangulation that Blair and Clinton used to do (having seen right beat left too many times, they found that new left could beat old left and new right) – except that for UKIP, it’s the other parties doing all the work for them.
Yes, a higher media profile for the BNP may well help the BNP, but it could end up helping UKIP more.