Acronyms can be tricky things... just imagine that you were a USN Admiral who asked for a flotilla of destroyers only to receive Shermans in skirts!
I see Parrish, Lakeman & Motley as kind of a "supergroup" of light anti-aircraft mounting designers. I like to think they all had beards and flared trousers.
I was in the bath, changed and back home watching Match of the Day while you carried on playing - I take my metaphorical hat off to you sir....
I have to say, I suspect this whole PLM thing is a bit of a rabbit hole, and in 20 years' time I'll be still be on this thread saying "Actually, I think the 'L' stands for something different...."