Ok, I read the bug report on console-setup-mini and there are
many. Someone suggested moving xorg.conf (yes, I still have it) out of the way and then doing the upgrade. It worked a treat. This seems quite a common problem in Debian systems so if you're reading this and you still have an xorg.conf file sitting in /etc/X11 then just rename it and that should sort things out.
Oh, and don't forget to move xorg.conf back once you've done your upgrade.
jdk