Some interesting points there. I’d not factored in anything for a sympathy vote in my thinking. I don’t think councillors get much recognition (I would certainly be unknown to more than a handful of Shaftesbury residents) but you aren’t the first to suggest this and it might well have been a factor.
Development as an issue was something I’ve heard from a few people too, and Queenstown is certainly the place that bears the brunt of new development. So, again, it probably played a part in the election result.
In both cases though, it reinforces the analysis: this was a local by-election, decided by local factors. Not one that will trouble either side unnecessarily.