Since the last post I tried downloading and burning the installer CD instead of the Live
CD image. This one connects fine to the internet but fails at the point where it is
supposed to start downloading and installing the software. There seems to be a required
file missing. When I first tried it complained that Thunderbird was not available but
having tried a custom install without Thunderbird, it still failed almost immediately
giving a different missing file as an excuse. Partitioning, network etc all complete
without without a hitch. This means my previous Ubuntu 16.04 install is now gone so the
only way is forward...