[k1m]

Media Lens have done great work analysing the Guardian's output over the years, particularly their support for wars: https://www.medialens.org/?s=guardian

I think anyone really interested in the Guardian's failings will learn more from Media Lens than any self-critical piece published by the paper itself.

Their books Guardians of Power and Propaganda Blitz examine the Guardian's output too.

(Disclosure: I'm currently the webmaster for the site.)

[drcongo]

Media Lens' reporting on The Guardian's Corbyn smear campaign was exceptional.

[thinkingemote]

You might possibly be interested in newssniffer which tracks changes to articles.

[k1m]

Thanks, it's a great site!