A 5 point drop in Corby during a by-election wouldn't be too problematic for the Tories.
I agree.
In fact, the Conservative vote has held up stronger than I expected. It's definitely helpful that UKIP isn't standing.
And if the Tories drop 5% nationally? Not a problem?
Not really, no. Although I'd prefer our polling numbers to be higher.
Governments are rarely popular and often suffer low polling numbers after their honeymoon period, however by election month, the polls often narrow quickly as the decision between a 'protest' vote for the Opposition and actually electing a government are different. If we were 5% behind come April 2015 (or whenever the election is), then I would be sh*tting it, to be blunt.
P.S. I presume you are talking about polling, lol.