http://may2015.com/category/poll-of-polls/
Click latest polls to see the last few months, hovers around 14/15% for UKIP. Down on last year of course, but doesn't look like it is sliding.
That's what i have been saying. But DP jumps on the 10%-12% polls and point to a slide when it's outdated data.
There also seems to the strengthening of the polls at the 15% mark this week as there have been less of the lower end ones and a tightening up at around 15%, i wouldn't be surprised by next week we'll start to see a couple of 16% ones thrown in there unless YouGov start shuffling out UKIP supporters from their database again