Terry says: “Magrat is pronounced Magg-rat. Doesn’t matter what I think is right—everyone I’ve heard pronounce it has pronounced it Maggrat.”
“In Margaret Murray’s book “The Witch Cult in Western Europe” you will find a number of Magrats and Magrets, and a suggestion that they were not misspellings but an earlier form of Margaret; also in the lists of those arraigned for witchcraft are the surnames Garlick, Device and Nutter. No Oggs or Weatherwax’s, though.”