There was a fairly detailed article on shunt-regulated amplifiers in Wireless Engineer 1951 May, p.132ff. It is available at:
https://www.americanradiohistory.com...er-1951-05.pdf.
Re the origins of the cascode, I think it was really quite simple. The question to be addressed was, in situations where, with wideband radar IF strips, noise considerations made it desirable to use two successive triode stages at the input (a single stage having insufficient gain to minimize the noise contribution of a following pentode stage), what was the best way, out the nine possible combinations, to arrange this triode pair. The answer turned out to be a grounded cathode stage followed by a grounded grid stage.
Cheers,