I think you may have been right. It was 28mm. The actual gaming tables involved something like 450 sq feet of playing area and then there were the off-table areas that held reserves and map moves to move between or to various parts of the table.
As far as all the 28mm figures in New Zealand - My guess is over 7,000 infantry models, over 1100 cavalry models and well over 200 model guns (and their crews, lots of limbers etc). There were more command and general figures than you could shake a stick at.
I just cannot wait to see a few photos that were taken with decent cameras.