I have been doing a little bit of research into 16th century herbal medicines, and it appears that many of them had some very nasty side effects, which could cause all sorts of problems.
Anyway as we all know Anne suffered, a miscarried in 1536 which was part of the reason for her downfall. (she may have suffered another miscarriage or still birth in between this one and Elizabeth birth. Some scholars say yes she did whilst others say no. Either way I will leave this question open to speculation)
Anne blamed Norfolk (the odious, cretinious jumped up poppinjay) for her miscarriage, and certainly at the time she was under a lot of stress and Norfolk’s actions on that day of Lard’s accident wouldn’t have helped her feel any better.
I feel that she was so stressed after Norfolks revelation that she would have perhaps been given a posset to help her to calm down a little.
One herb which has leapt out at me is Peony, this herb/flower is extremely poisonous, if injested in large enough quantities it causes death, however in smaller doses it causes instant miscarriage. Is it possible that the posset she may have been given that day contained along with other herbs, Peony?
If so was the person who made up the posset aware of the affects of Peony? Was it possible that the person was paid a large sum of money to put Peony into the mix. Or was it purely accidental?