A partial update ... I've been sent a copy of a letter written to the school by a Canadian couple who encountered the school group at Pelion Hut. PWS now has that letter as well. The Canadians don't pull any punches in a long letter, using words like "shock" "dismay" and "disappointment". I'm not aware of any response from the school as yet, but I hear that PWS is looking into the whole situation. I am told the school was given clear guidelines on group sizes, and use of facilities. It seems this may not be a first "offence" from this school.
The general line from PWS is to encourage
responsible visits by small, well-supervised groups. And they tell me that most of the time this approach works. But in this case ...

Anyway, I'll let you know if I hear any more.
And by the way, other than that experience, the Canadians say
we thoroughly enjoyed our time on the Overland Track and in Tasmania
cheers
Peter