Okay, so it wasn't a really great day. I managed to damage the USB2 connector on my trusty old Canon HFS10, rendering the 32GB of on board memory inaccessible. It is far enough out of date that I won't spend the money to repair it, I can still use the SD card.
I just had a look at page 91 of the owners manual (downloaded a pdf copy from the Canon support website) and it indicates that you can transfer the files (Copying Scenes) from the internal storage to the SD card.