Just managed to try that – has no effect. The error remains. It’s very strange. The page is clearly there in the database – I can edit it fine, and its summary and featured image pop up fine in the category page.
No worries, I renamed the plugin directory first so I had the option to bring it back if things went bad. It worked fine and WordPress deactivated the plugin perfectly, so I could log in.
Any thoughts? What happens if I go into Cpanel and delete all the WP-cache plugin files that way? Will it fry my installation or will WordPress recover OK?