Tactical voting, so much talked up amongst progressives before and during the 2019 GE campaign, was in the main a failure as it did not deliver what those running the the sites expected/wanted and all but promised.
I think the first failure was a lack of understanding of the mind set of voters. Yes at face value if say Labour were the best/2nd placed in a particular constituency then the third place Lib Dem voters could be asked to support the Labour candidate. But being asked is one thing, what the voters actually do is another. Some would follow the advice, others would not and they’d either stay with the Lib Dems, not vote or even vote for the Tory if Labour being elected was their worst nightmare. Also, particularly in the case in the 2019 GE, where the Labour candidate was not an obvious and well known EU Remain campaigner there would be a big issue for Greens and Lib Dems. Of course the other issue not being picked up, although I fail to see why, was that Labour was itself leaking votes to the Tories mainly because of electors dislike of Jeremy Corbyn.
There were clearly some seats, particularly where the Lib Dems had either come close or won them in the past where the 3rd place Libs were probably the best punt to topple the sitting Tory. I say this as some ‘soft’ Tories may well be persuaded to vote Lib Dem whereas they could not pushed to vote Labour.
Secondly, what was going on where the tactical voting recommendation was to support a known Labour, sometimes very well known, Brexiteer candidate. Progressives be they Green or Lib Dem were never going to back them. Those constituencies where at face value Labour were the best placed to take the seat from the Tories but the Labour candidate was a Brexiteer needed far more careful thought.
Thirdly, Labour’s intransigent and stubborn refusal to engage with the Remain Alliance parties, Lib Dem, Green and PC should have triggered alarm bells. Yes, Labour were shouting from the roof tops that other candidates should stand down to give them the best run at various seats but their response to Labour being asked to do the same thing to assist Lib Dem, Green or PC candidates was ‘NO’ every time.
My feeling some time before the election was announced was that People’s Vote were too concerned with pandering to a Labour Party who would not cooperate with anyone else instead of challenging their ‘our way or no way’ dogma.
My final thought is this, it’s all well and good crunching all kinds of polling data but without sensible feet on the ground the individual factors that affect how real people will actually vote in a constituency can’t be understood and indeed it was not understood. This to me was so obvious from those seats where those recommending tactical voting changed their minds about who to back part way through the GE campaign. When I first heard they may do this more alarm bells rang with me as to my mind if they did it those seats would all but be handed to the Tories on a plate because of the confusion it would cause. Of course they did it and my present understanding is that the effect was just as I had thought it would be i.e. the seats were all but handed straight to the Tories!
PS. In some seats where the Lib Dems were within touching distance of beating the Tories Labour canvassers were quite obviously and deliberately being sent out to tell voters that Labour was in fact the real challenger in that seat. The ploy was to get them to vote Labour so the seat could not be taken off the Tories by the Lib Dems!!!