I42 you have read the wiki I expect. In this application they would be used as in the last line, not for measuring wavelength but as a tuned circuit in the oscillator. Not vast
¼ λ at 170 -230 Mhz not a lot and inside the box I would think.
The question is why did Qantas alone have this device given at the time they were known as Qantas Empire Airways and did nearly everything in lockstep with BOAC
That is a good question, must have been some strange Australian reason as, as far as I am concerned it is purely a military aid. I never did it on my training at college, maybe I'm too old I was only licensed in 1972.