I’ve been looking at this further and no longer believe it to be a case of the upgrade. I upgraded to the beta and also downgraded back to my original version but still have the same issue. I also put the template and posts onto my blog which uses 2.8 and again the same problem. So at some point something had happened for it to no longer display theauthor of posts. I haven’t changed anything except upgrade and add plugins, so I’m totally stumped.
Out of interest, how does the php code know what the_author is? Where is that declared?