A word to the wise: when upgrading your WordPress installations, always remember to deactivate your plugins before you start.
Yup, I overlooked / ignored the recommended steps for upgrading and managed to screw things up somewhat. Apart from the absence of posts (like that’s anything new) you have not likely noticed anything actually wrong but suffice to say that the admin pages were unusable for a while.
All is well again now though and a flurry of posts will ensue . . .