Get the appropriate version of the VirtualBox extension pack installed – I found the correct version in here: Download VirtualBox (Old Builds): VirtualBox 4.2
Add self to vboxusers group as per Set up USB for Virtualbox. Must reboot for change to take effect.
sudo usermod -aG vboxusers
Then follow the additional steps. For Windows XP at least, must add a filter before opening so that the USB is recognised by the File Manager and displayed as an extra drive.