Ohh... I relented and when in Asda, I had a look and actually purchased the mag.
As well as the cap TD kindly posted,
and the article on page 19 about the BT Test login which jid mentioned.. and another pic (whoops they should have actually done the BTwspeedtest).
Theres also a separate bit on "Step by Step - How to check you line's capabilities".
.. and yet another screen cap and link to frogstats.