From Frank En Eva (1973). The difference between a hobbyist and a historian? The hobbyist (that's me) notices that lots of these side-zip platform knee-scrapers show up in mid-70's Dr Who's and Benny Hill's, dubs them "Benny Who" boots and moves on. A historian (that's AndyP) does extensive research and creates a chart that shows exactly where these boots belong on the evolutionary flow chart(I've probably mis-named the "tree," but I'm too lazy to find its proper name). I have a gut-feeling, backed up by years of casual observation, that these boots were infinitely more popular in England and Europe than the States. Andy could provide actual evidence.
If you're not checking out Andy's tumblr-
You're missing some great vintage boots.