The fate of King Edward V and his brother Prince Richard Duke of Yo

Has anyone examined the writings of Dr Argenti, a member of the young
king's household, who subsequently became provost of a Cambridge
college, to see whether these throw any light on the fate of the two
boys?

Dr Argenti was said to be devoted to Edward V and his father.

Also, when did Prince Richard of York lose his Dukedom of Norfolk,
which was taken away from him and given to one of the Howard
claimants?

This couldn't have taken place in the young prince's lifetime. Or
could it?