Ludlam's accomplishment was to highlight the meaninglessness of the metadata/content distinction with examples everyone can grasp:
- If you log into your home broadband router and send an e-mail, “metadata” (such as the recipient of an e-mail you send) will be captured;
- If you log into a friend's broadband router, the same information will be collected (associated with your friend's router's IP address);
- If you use Gmail from either of those two, the metadata store will reveal your contact with Gmail (HTTPS should hide the rest of the session;
- If you use a university WiFi network, or a hotspot in a cafe, your metadata won't be stored. That's because in both cases, any obligation ends at the customer (University or cafe) and its relationship with the carrier (AArnet or someone like Telstra).
http://www.theregister.co.uk/2015/02/04/this_one_weird_trick_hides_your_metadata_as_content/