Thanks for the replies, folks.
No, I haven't tried that, even though this update alert has been appearing for a couple of weeks now. You'll see below why that's not an issue now.
Your eyes are better than mine! I hadn't noticed the change of case. (':oops:')
To quote that well known Roman saying, a funny thing happened on the way to the forum...
After I had posted into this forum, the contents of the update alert changed. Now, instead of all the packages listed above, there is a single package which is not part of that list. In other words, since posting to this forum, the problem appears(!) to have fixed itself.
Hmm, curiouser & curiouser...
Thanks again for the replies. Let's just hope that the problem stays fixed.