Hi Michal, thanks for your prompt reply, so now it seems to kill my X session (well sort of my machine really) but if i ssh in from another computer first I've been allowed to run the logging thing. So please see new logs here:
chrisd-ubuntu_2017-05-15T14%3A40%3A54.385996.zip
displaylink_while_plugged.logs.tar.gz
Many thanks
Christopher