Daily Mirror is left-wing as is The Independent. Both are prominently featured in the screen shot, along with the Guardian, which you already mentioned. Either you're very poorly informed about the different papers political leaning, or not very observant.

Also, more of the best-selling papers are right-wing than left, so it's natural there will be more.

https://yougov.co.uk/topics/politics/articles-reports/2017/0...