Hello amd, I thought I'd have a little search about... I found mention in Andy Burnham's book https://archive.org/details/theoldstonesofthenorthofenglandisleofman.afieldguidetomegalithicandotherprehistoricbyandyburnham/page/n69/mode/2up?q=%22long+meg%22+whisper&view=theater
Hmm, you'd better ask him. He's the Megalithic Portal Person, if you're unfamiliar.
Of course, he might have copied it from wikipedia. In which case you're on a hiding to nothing :)
But even if it is a new idea, perhaps it's worth trying out I guess
