I have confirmed that my six panels I received came from a Beveridege 2WS set of speakers.
Considering the small number of these speakers made and even smaller number still in being used regularly, there may not really be much of a market for the panels anymore.
So, the question is, to what purpose should these panels be used. Building new custom speakers with ancient panels does not seem so logical wihout the availabity of suitable H/V amps to match them properly, and building such amps is beyond my skill set.