I haven't been on here for a while and just spotted this thread. I found my Wonder lights in the garage, I've also got some of the later black ones that looked similar, guess they are the Ever Ready ones.
the beauty of them at that time were that they were the only easily removable system out there, so were good for evening chaingangs on a good bike. The alternative was to bolt on (semi permamnently) an ever-ready or poss attach it via toestraps under a backpack and let them point skywards.
My favourite was to use the wonderlight bracket mated to a front ER light to give a better beam and still be portable and a WL rear - in both cases using old inner tube to stop slippage.