(08 Sep 2015, 7:27 am)GX03 SVC wrote Whatever booklet the guard was reading in his cab must have shown it as Blaydon-Sunderland. He can't mistake it for a Rover after having a long look at it...!
From the bottom of the Explorer page;
Your screenshot actually alludes to Network One passes (including Day Rovers) as it states 'The Only One (big clue here!) For Unlimited Travel On Any Bus, Metro, Train And Ferry* Across Tyne And Wear!'. Now, as we all aware, the scope of the Explorer ticket extends beyond Tyne and Wear encompassing much of the north east. Therefore, if the text applies specifically to Explorer tickets, it should read something along the lines of 'The Only One for Unlimited Travel on Any Bus, Metro or Ferry in the North East* and trains between Metrocentre and Sunderland'.
If you look to the right of the explorer page (as well as the actual leaflet), the literature clearly states the ticket is valid on trains between Newcastle and Sunderland only. Aside from the website, where generic Network One advertising, terms and conditions are stated, the leaflet does not include 'The Only One (once again, big clue here!) For Unlimited Travel On Any Bus, Metro, Train And Ferry* Across Tyne And Wear!' statement.
http://www.networkonetickets.co.uk/docum...t_2015.pdf
It's worth noting that the leaflet was updated as of August 2015!
As I've said, I've travelled between Sunderland and Metrocentre on an Explorer without being challenged. However, the guards initial judgement was probably the correct one in your case. May I suggest printing, or obtaining a copy of the leaflet and see what the guard does when the leaflet is produced. My guess is, you'll have to pay the fare!