On Sunday, Mike Smithson over at Political Betting reported that the Sunday Times had altered the figures reported on the YouGov survey to reduce the Tory lead from 6% to 2%. At the time, I commented that this poll seemed like an outlier and further confirmation was required. Today's poll from YouGov, published in the Sun, extends the Tory lead back to 7%, ascribing the 5% shift to Cameron's speechifying in Brighton.
This seems like a big leap based upon one speech which was generally received with mixed results. I would posit two alternative theories.
One, that Sunday's poll was an outlier and gave a freak result just outside the margin of error.
Two, that the Sunday Times took the worst possible outcome from the poll as the headline figure to try to create a Tory bounce.