In the absence of any replies to my OP I decided to reformat the 7.44GB USB stick and start over.

The new installation has both persistence and encryption and the CLI 'df' now accords with Figure 8 of KK's March 2013 article in Linux Magazine. Hope this helps other newbies.

One observation: it would make the input of an encryption passphrase during loading much easier if there was a 'show passphrase' facility.