I read a fan essay online which argued p. convincingly that the DEs were based pretty strongly on the IRA, which would have been an obvious source of inspiration as the Troubles were ending just as J. K. had started writing.
Riddlemort woulda been a better direction to take Voldy as well. This murderous psychopath with good looks and a dark charisma to him ... infinitely preferable to the cackling Skeletor-esque bad guy we got.