Just one of many points open to lively debate, eh?

Case #2 with common N/Gnd conductor and multiple rods is starting to look very much like our PME (Protective Multiple Earthing) distribution system here - Except that it's within the customer's premises instead of the utility's system.

Because we have neutral & ground separation at the main panel, obviously this extends to a sub-panel in an outbuilding. Sometimes an extra ground rod is used, but it's not specified as a requirement by the IEE.

In fact, in an older installation which uses a voltage-operated ELCB (if you can cast your mind back a couple of weeks!), and extra rod must NOT be used, or it could render the breaker inoperative.