Well, I've just read about this and clearly it's getting late...

Well, I've just read about this and clearly it's getting late for me because the numbers are doing my head in.

Anzon had 50% and now has 40% So in fact they sold 20% of their individual holding. If they only sold 10% of their holding they would have 45% left.
So Anzon got A$123M for 20% of its individual holding.
So Anzon's future earnings from this field will reduce by 20%

Same for BPT.