What are these conenctors called?

[Mike Watterson]

I do think they might have originated in 1938 or 1939 as power connectors to replace wander plugs on HT packs, particularly 45V and 90V. Maybe even some USA 1.5V LT packs in 1938 when the Sylvania 1.4V filament octal tubes were released. But I've never even seen a part number for the sockets or plugs.