I have always voted Labour, and have often been a member of the Party, campaigning and canvassing for them. For what it’s worth, here’s my feeling about voting Labour next General Election:
2. If a new socialist party starts up, it could easily hoover up many of the 200k former LP members who have left in disgust (I’d join), and perhaps also pick up union affiliations. They could become the second biggest party by membership quite quickly. Our voting for that could rapidly change the political landscape in a way that would make it more reflective of public opinion (see below). I strongly support that.
3. Our voting for an alternative party that’s to the left will cost Labour votes in key marginals, and that prospect will scare them. Just as the Brexit Party was hugely influential in shaping Tory policy without winning seats, a socialist alternative party could be equally effective, forcing the Labour Party to move left.
4. The Labour Party is now run by people many of whom worked against a Labour victory under Corbyn, celebrated the fact that he lost, endlessly smear thousands of decent people (like, I think, myself) as trots, thugs, antisemites (see this), homophobes, terrorist sympathisers, etc. and who would rather burn the house down than allow someone with my sort of mild leftwing (by European standards) politics get anywhere near power. Why would I vote for people who despise me, want people like me out their party, and are so hostile to the kind of policies I favour?
5. If Labour win next time, it will cement forever the narrative that the left can never win (when in fact they achieved a hung parliament in 2017 and probably would have won with another week of campaigning given their upward trajectory under the press moratorium (see image),
or if their own MPs hadn’t been constantly sabotaging their party from the moment Labour pulled ahead in the polls (see image below on polling before and after the infamous 'Chicken Coup' that Labour MPs staged just after Corbyn went ahead),
despite the party having policies that the public actually liked, as this short video illustrates:
6. Kier Starmer is a habitual liar and, frankly, a backstabber who betrayed the Party membership. I don't want people like that in power.
True, not voting Labour could conceivably let the Tories in again. However, that's highly unlikely. Realistically, the most that socialists not voting for Starmer's Labour is likely to achieve is denying Labour an outright majority, forcing them into coalition with the (far more socialist) Greens, etc. If you give a high priority to getting PR, and even many centrists do, then that is actually the best possible outcome. The alternative to not voting Labour is almost certainly not 'letting the Tories back in', and in fact may be even better than an outright Labour victory.
In any case, even if it were just a matter of 'keeping the Tories out', I think we now need to play the longer game. Currently, neither main party is likely to do anything to reverse growing inequality and privatisation, despite the fact that the public favour that. Inequality increased even under New Labour:
For decades, realistically, our choice has been between two options: to put into Government a party that allows inequality to increase more quickly or else a party that will slow that growth in inequality down a bit. But the direction of travel is always the same: growing inequality. Somehow, we need to get a party in to power that will reverse the direction of travel. Voting for Labour next time makes it significantly less likely we will ever be able to do that.