Ah, so sheer speculation. You have no data or info to suggest this would be the outcome of such a vote, but it might, so whatever. Strong stuff! More fool me for thinking that when you invoked voteshare and turnout you had anything to show for it beyond a wish.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".
It needn't be confined to existing trends. But to have credibility, it needs to be based in something substantial. You're generally disconnected and reductionist about non-American politics, so this isn't unexpected-- but if all observable data points in one direction, it's not wise to put your hopes in a wizard granting your wish in the opposite direction.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".
Observable data suggests strongly that the Tories being in power for eons shifts the political window-- and Labour-- to the right, not the left. Observable data suggests that a third manifesto in a row promising nationalisation losing to a continuation of hard-right austerity will send exactly the opposite message than you want. Observable data suggests that avowed socialists in the UK have torpedoed their own political relevance through being so incredibly unreliable as voters, and that we're a small enough constituency to begin with.