What I find interesting in the briefing room scene in “The Cage” (and the re-used footage of it in “The Menagerie”) is that there is an empty chair at the table (presumably Captain Pike’s) that is a different model Burke chair than the standard ones used through the series both with modified and unmodified backs (models 115 & 116).
I seem to recall it was bought up/mentioned in another thread that it is the Arthur Umanoff Swivel Office Chair.
The Mid-Century Modern chair was designed by Arthur Umanoff in the United States and was first made between 1960-1969.
It is built out of enameled steel, vinyl and Walnut
39 in. H x 24 in. W x 24 in.
99 cm H x 61 cm W x 61 cm
Seat back height: 18 in. (46 cm)