Here’s the national equivalent vote share* which Ukip has secured in the last three rounds of local elections. Notice a trend?
* National equivalent vote share is a standard calculation carried out by Thrasher and Rallings to allow vote shares to be compared between different years. If you simply took the vote totals for each party each year you would run into the problem that not the same seats are up for election each year and so the year by year figures are not directly comparable. However, what Thrasher and Rallings do is adjust each year’s figures to show what the vote share would have been had the whole country been up for election – and these figures are comparable year by year.