ZeeBee, thanks. Stopped and restarted the print spooler service on the Dell.
Tried to print a test page twice. It is shown on the iMac Canon icon as 2 jobs waiting but nothing happens.
I also notice that there are no flashing lights on the router when I hit print so presumably the signal is not leaving the iMac to the router.
Any settings I need to make here?
mcdhu