OK...

Start menu - run command - update-menus -> the command is accepted and appears to complete successfully, but with no errors or messages of any kind (whether run as is, or in a terminal window). There are still 'no entries' above 'Bookmarks' in the start menu.

The error message for Konsole from the taskbar (is this the correct terminology ?) is in fact 'Could not find the specified service System/konsole.desktop'.