Thanks for that lead.
My sda1 is a FAT32 formatted 4GB USB stick and it seems that "You can't modify permissions on a FAT filesystem. You can give the whole system default permissions when you mount it though, using the umask option to mount, which you can also throw in your /etc/fstab file. Try (replace XXX with your user is and group id): /dev/hda1 /winc vfat uid=XXX,gid=XXX 0 0"
Using sudo has worked so far and being the sole user I'll soldier on until the problem has to be fixed.
As this question hasn't cropped up in the four or five other distros I've used on FAT32 formatted USB sticks maybe it'll be a non-issue.