OK, maybe bad style to respond to your own messages, but after 2 evenings of digging, I think I've found the answer.
I had downloaded a patch update from
www.ampfea.org which was suggesting that you could write to banks A and B then STORE TO FLASH, from whence you could overwrite banks C, D, E, F, G and H
However, I now think that STORE TO FLASH is a feature only available in the recent OS updates for other models of the Virus such as the Indigo. I am now assuming that as I have a Rack Classic, I can't use this feature.
So, am I right? And how do people on here store their banks if they can only store to and over write A & B?