Right I am buggered. I cannot expand the C: partition as it is the boot partition. As I suspect Vista and my (modest) 8GB of transferred data (it worked so far) consumes 38 of the 48GB I have on the C: drive. I have deleted and formatted the Linux partition but it is a pain in the butt that I could not do that during an upgrade clean install.
Although now I have deleted the Windows.old folder I have reclaimed a load of space.
You know what? Vista (with my elderly Nvidia card) looks like nothing so much as Linux (Gnome) who would have thought!