The Conservatives are 5% ahead of Labour. Not as slim a margin as one might suppose. The Conservatives have since 1992 consistently performed better than their poll ratings. It is the closet Consevative phenomenon. Many people feel they cannot admit to being pro-Conservative in polite society. Cf: Northern Ireland where surveys always overestimated the middle ground. People are often unwilling to admit to their more extreme views to a stranger even in an anonymous survey. The Conservative Party was seen as being beyond the pale by many of the chattering classes.
The allegations regarding Byers et al have come at precisely the wrong time. I do not assume that he is guilty. I believe in giving people the benefit of the doubt.