I remember them having stacks of these and one or two others on the checkouts at
GW shops, back around the early eighties. I couldn't say if they were shipped with WDs or other mags but I bet they showed up in boxed games like Valley of the Four Winds. That was a time when
GW's rapid retail expansion had mainstream consumers buying everything from executive toy puzzles, jigsaws, chess computers, go sets... (ad lib to fade) This reminds me of the sort of thing that got stuffed into every carrier bag.