If Ukip lose votes, who will get them?

More than most elections, small differences in votes are likely to decide who ends up on top in May. So alongside the big picture challenges facing the parties, such as over leadership, the economy and living standards, are things that could change one or two per cent of votes and so decide the outcome in a dozen seats that will separate victory from defeat.

One of the toughest conundrums concerns Ukip. Will they retain their current level of support—around 15 per cent—or will they slip back? And, if they do slip back, who will benefit? To have a stab at answering this question, I have been crunching data from 83 polls that YouGov has conducted since early October. The Labour-Conservative race has been tight throughout these past three months, during which we have questioned more than 130,000 people.

Ukip’s support has fluctuated between 13 per cent and 19 per cent. To explore the impact of Ukip’s rise to different levels, I sorted our 83 polls into three groups: those where Ukip’s support has been 13-14 per cent, those where it has been 15-16 per cent, and those where it has been 17-19 per cent.

These are the average voting intentions for each of the three groups:

On average, Ukip’s support is almost four points higher in the third group than the first. Just over half its “gains” come from the Conservatives, with smaller shares from Labour and—wait for it—the Greens. This bears out anecdotal evidence of some protest voters oscillating between the two very different parties outside the Westminster establishment. Support for the Lib Dems and “others”—mainly Scottish Nationalists—is unaffected by the level of Ukip support.

This matters because it throws light on what might happen if the Ukip vote is squeezed in May. There are two schools of thought. First, Ukip continues to draw most of its support from people who voted Conservative in 2010 and, if they don’t stay with Ukip, will return to the Tory fold. Second, although Ukip’s initial surge was mainly at the expense of the Tories, their more recent gains, taking them from 10-12 per cent to the middle and sometimes high teens, has been more broadly based; so any reduction in Ukip support to, say 10 per cent, in the election will do nothing to help the Conservatives to fend of Labour in the Con-Lab marginals.

Now, nothing is certain. As a financial advisor might say, past performance provides no guarantee to what will happen in the future. But these figures support the first school of thought, and suggest that if Ukip’s support is squeezed in the next three months, the Conservatives will reap the greatest benefit.