Thomas obviously flilled O`Brien in on Mary entertaining Pamook in her room.. Or so we're led to believe, So, with Daisy floundering on what she knows, she puts O`Brien at risk, for being in chaoots with Thomas.
However, I'm now falling more into the thought that Pamooks death is something to do with Thomas, and not natural causes. Pamook rebuffed Thomas's advances. and did Thomas not serve Pamook a drink just as he was about to enter Marys room?
*might have got the spelling wrong on Pamook,*