Labour's fragile poll lead

An interesting little experiment in this weeks Opinium / Observer poll was that we asked people if their reason for voting Labour, for example, was to vote for Labour or vote against someone else.

Unfortunately not enough people (from a research perspective) said that they were mainly voting against someone else for us to properly look at who they're voting against but we can see what proportion of each party's voters said it was partly or mainly to vote against someone else:

Labour: 32%
Conservative: 25%
Lib Dem: 28%
UKIP: 32%

By comparison to the last time we had a Conservative prime minister, Labour's poll lead is a lot smaller and this is for two reasons. First, opinion polling is much better than it was in the 80s but more importantly, the fact that we have an almost multi-party system means that the Labour party is no longer receiving as many protest votes as it might have during its last period in opposition.

Still, the fact that the Labour figure is higher than that for either governing party shows why Labour's lead is liable to collapse every so often. If people are voting for you mainly to oppose someone else then it's hardly surprising that they're the quickest to desert if circumstances change.