thank you Andreas Bernauer for your response.
I tried your suggestion this morning this is the result:
[awp@localhost ~]$ xhost +localhost
localhost being added to access control list
[awp@localhost ~]$ su root
Password:
[root@localhost awp]# xhost +localhost
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified
xhost: unable to open display ":0.0"
[root@localhost awp]# kdesu pup
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified
kdesu: cannot connect to X server :0.0
so neither command resolved the issue.
--
Diolch yn fawr, Ashley