Re the reference to the previous thread... this is a lot of very useful information on the subject, it would have been helpful to have found this earlier. I have printed it and will work through it in slow time. That said, I think I have now got the bits I needed working.

for the xdmcp into remote server/s:

X -broadcast :1

and when inside knoppix desktop:

xhost +ipaddressofappserver

Re the missing Ctrl+Alt text from my previous posts, thank you. I just thought my keyboard had been playing up and had already thought to replace it. I re-read my posts each time and wondered if I was loosing my marbles, surely I could not have made so many typing errors. I guess I should 'read the documentation'.