They are early KEF monitors made for BBC, later became famous LS3/5a.
I don't think they were fools. The woofer was good to 2khz.
Dispersion control? Radiation enhancement? Compensation for volume of frequencies short enough?
I made a guitar amp with square holes, well speaker cabinet, with ancient alnico drivers, out of plywood without plastic and crap all over it, just some stain and paint only on sides, bottom and top. It sounds amazing for a nearly untreated pair of 10's. The sound in size is 10 times bigger than the fender speaker in the amp I used to power it. I mean it doesn't sound loud, it sounds huge. The fender sounds like a tiny loud thing stuffed in a small space by comparrison.