OK, progress of sorts.
I have now attached the PC running Ubuntu 12.04 to a Windows 7 PC via an ethernet cable. The Windows 7 PC has an internet connection.
The signal icon in Ubuntu is animated and I assumed this meant it was connected to the internet. However, it is not.
When I look into the Network window, it says a wired connection is connecting. But, it never connects.
Any ideas or solutions greatly welcome.