DozyWannabe,
"In any case it was largely acedemic as all but one flight had approached Antarctica in brilliantly clear conditions and the final letdown was entirely VFR with no need for instrument cloud break procedures."
You say,
"it was not the first such descent made, and in fact ANZ had been quietly removing layers of safety for two years prior to the accident"
Which is where I disagree. It was the first descent made in marginal weather conditions, we have a record of flights descending below the laid down minima, but they were all carried out in "brilliantly clear conditions".
If you want to break the rules you must make sure everything is going for you, that was possible in Brilliantly Clear Conditions.