If we ignore the undecideds, this seems to make it quite likely that the Tories will secure a majority in parliament even as more voters prefer left-of-center parties. In Canada’s 2006 election a majority of people voted either Liberal, New Democrat, or Green but the Conservatives wound up with the most parliamentary seats and they’ve been running a minority government ever since even though it’s pretty clear that the median Canadian was supporting the Liberals. Most countries with strong multi-party politics have a substantial element of proportional representation in their system which helps iron out these kind of bugs. Canada and the UK, however, do first-past-the-post elections in single member districts.
Fun With Multi-Party Politics