The Guardian newspaper is read by a declining readership and as a business is I believe a loosing money.
BBC journalists use it as their default point of view despite the fact it represents such a very small proportion of our population.
During the review of the newspapers on BBC 2's Newsnight at the end of the show the Guardian gets a far greater showing than the the far more popular Daily Mail - if you don't believe me clock it for yourself!
Tonight on the 6 and 10 O'clock news on the item showing the Editors leaving Downing Street 3 Editors were asked for their comments and the longest of the three, which include the journalist and Editor side by side, was the one with the Guardian which was also the third and last thus leaving the viewer with the image of the Guardian Editor.
This is subtle bias but bias none the less!