One wonders why you brought up those factors, then, if you were just going to insist they're irrelevant. Any, digress.
What is irrelevant is that you are talking about past elections. And I am talking about a possible scenario in the future. Those factors are all relevant data when interpreting an election-- whether you're just some guy or a Labour functionary. I didn't say "look at these past results, there lies the strength of my argument", I said (paraphrasing) "you're interpreting the possible results of a future election in which Keith loses with just one single measurement and idea when there are many more to be considered".
Do you begin to understand how inane your criticism is yet? And you said you understood the argument. It'd be one thing if you were just lost, but you are confidently out in
left right field pretending you've made any kind of a point.
So: if your novel scenario isn't based on any existing trends or factors, what exactly is it based on?
The possibility of Keith losing because the left rebels from the extortion and backs another party instead of continuing an abusive relationship with Tories painted red. It would probably take some organizing. Novel things often do. And you're literally calling it a novel scenario, why would it be confined to extensions of existing trends, especially ones measured in past elections? There
are factors militating in that direction, of course, but also naturally against. In the 'for' column there is the fact that, despite your characterization of Keith's manifesto, there are plenty of reasons for the left to despise him and for others to recognize that they have cause, or indeed that they should join in despising him and Conservative "Labour".