Back in 2005, there was a discussion of drinking blood as an Irish
practice and I finally found the reference I remembered. It was
description written by Edmund Spenser after witnessing the execution
of Murrough ÓBrien at Limerick in 1577.
“An old woman, which was his foster-mother, took up his head
whilst he was quartered, and sucked up all the blood running thereout,
saying that the earth was not worthy to drink it . . .”
I'm not trying to revive the discussion, just to add a bit of
information. I hope it's helpful!