It would require a book to explain it all.

There is a movie coming out which gives the background:

https://www.theguardian.com/film/2019/jul/23/the-great-hack-review-cambridge-analytica-facebook-carole-cadwalladr-arron-banks

The Great Hack. Worth a look. Things have moved on of course.

Here is a link to what is actually going on:

https://www.theguardian.com/business/2019/aug/11/brexit-was-becoming-farce-now-turning-into-coup-johnson

I'm with Neal Ascherson and Ferdinand Mount in this collective opinion article in the London Review of Books:

https://www.lrb.co.uk/v41/n16/the-state-were-in/how-bad-can-it-get