Thank you for getting back to me. I did more reading, played with vncpasswd and figured out how to use the secret file. I've tunnelled vnc through SSH to tcp/5900 and got a grey screen. It has to be over 10 year since I last used vnc, and then it was on windows clients! Thoughts so far Inc, is SSH causing the problem, or have I got a config issue with vnc. I can vnc directly to tcp/5902 and get a working terminal. Which maybe suggests SSH is the problem,but then again it might be settings specific to the tcp5900 instance of xvnc, been reading about ~/.vnc/xstartup (but from what I've read it appears to be server side config). Or I have a problem with my Kali machine. Going to spin up a Ubuntu VM in the morning. Plenty still to learn/try. I'm not hrowing the towel in yet.