It was one of those responses which I presume are (at least) semi-automated. I'm guessing a person or a process attempts to categorise incoming issues and hits 'send reply 20'. I did send some traces myself though so who knows how these things work.
Well Telstra got back to at 4.15 and said "We have located and resolved an issue with part of our network. Can you please retry this and let me know how you get on." and ... it does ! en.wikipedia.org working just fine (in fact seems faster than previously !).
Full credit to Telstra - this was 2:30 from my first report to resolution. Don't know why mine got fixed when sleemanj hasn't ... maybe because Allan Freeth is my dad (just kidding !).
Would be interested to what degree the fix has helped others ?