Just coming back to this thread by way of closure....
I've managed to get the WYSIWYG working with my template - I had hacked the template to include a masthead & navigation (i.e. to make it look like the rest of our site) and the navigation was a javascript effort. It appears that this was conflicting with the WYSIWYG system in DW, which I imagine is also javascript? If I included the masthead/nav in my template, no WYSIWYG - if I left it out, WYSIWYG reappears.
Ultimately I've solved it by deploying a pure CSS navigation system rather than javascript. Took a lot of fiddling around with the various css elements of both DW and the navigation system, but I have a working navigation AND the WYSIWYG is now working, too. Result! :-)
At the same time my DW has been successfully upgraded to the latest 'HRUN' version ( see thread
https://forum.dokuwiki.org/post/46456) - this spiked the template and required another long round of CSS meddling! And not being a CSS guru I burned a lot of midnight oil ;-) But we've got there in the end!
Many thanks to all who contributed replies or suggestions/tips.
Hugh