Spring loaded TEI lampholders

Have always loved these lampholders, real quality! Had some many years ago but lost them when I went through the impartial and not that interested stage of my lighting interest in my 20s. These came from a Leyland National bus, the once very common smokey, noisey single decker buses with the spinning fan visible through a grill at the back. The lighting was through the center of the bus behind large rectangular translucent panels, a very tidy arrangement.