This turned out to be a missing Me.Controls.Add(CuteEdit), so Cute Editor now displays OK initially in the Web Part thanks.
However, when I switch the WebPartManager to Edit mode , The toolbars do not render correctly:



Also, I have a second separate instance of Cute Editor in the Web Editor Part, which also displays as above. If I do not create the Cute Editor instance above in the 'main' Web Part, the Editor Part displays like this:

Any Ideas? John B