When someone leaves the University of York, their account is suspended which has the knock on effect that in Blogger your blog posts are written by "Unknown". You can still see the blog posts.
Worse than that, all the media uploaded by that person also disappears. See this post here.
I'm looking into the Blogger API to see if I can at least find a user's posts and re-create them as someone else as an awful workaround.
I've added an Issue to the Blogger forum.... tumbleweed ... and nobody is interested.
This all comes about because Blogger isn't a "Core App" of Google Apps but it's rubbish. Boo Google! At least let us be able to transfer ownership of blog posts or something. People regularly come and go at a University and hobbling their blog posts seems ridiculous. This may force us to have to think about using Wordpress ... which will be a shame.