WYSIWYG editor not present with WordPress
Well, finally managed to get CKEditor going, but this is far from an ideal solutuion. The problem is that an extra component is being put into the URL for the editor. My main site that works is mysite.org and the problem is with test.mysite.org. This has all its files in a subdirectory of the main site and this confuses things. Looking up [civicrm.root] in the Resource URL admin page shows an extra "/test". So work round for now is to edit CRM/Core/Resource.php to replace "[civicrm.root]" with "wp-content/plugins/civicrm/civicrm/" in the call to the editor. A bit of trail and error and a bit odd as that isn't logical from what I epxected [civicrm.root] to produce.

I would love a better solution.

Another problem How can I fix [civicrm.root] variable on an addon domain? was useful in confirming that [civicrm.root] is the problem.