This is all pretty unfortunate from People's Vote and Gina Miller. Soon we're going to need a tactical voting site to decide which tactical voting site to vote for. Perhaps they should concentrate more on campaigning and less on scooping up your data.
theguardian.com/politics/2019/…
theguardian.com/politics/2019/…
If you're interested in what actual independent polling experts have to say about the Best for Britain tactical voting tool, I'd take a look at this.
(For the avoidance of doubt, I have no links with @BestForBritain or its directors or donors: I have not worked with them, I am not aware they have made any donation in money or kind to @GoodLawProject or to me personally, and I don't see them socially.)
The passive aggressive our "recommendations are based 'purely on the data'" is classic Gina. Here's what she was saying to her would be donors during the prorogation case (which of course before we got to the Supreme Court we won and she lost). 
