In the late 70s, I worked for a company that built prototypes for the BBC, so spent quite a lot of time on the phone to the BBC tech people, trying to work out why the bits they had sent me didn't correspond to the circuit diagram I was working to. They were the people that had designed the LS3/5a (and all the rest) and it was their enthusiasm for the speaker that led me to buy a set in 1978. They were adamant that the speakers would only work if placed on a bookshelf, jammed between books, so as to emulate the placement in an outside broadcast van. They also said that they were primarily designed for speech, but the Third Programme people felt they were good enough for classical music monitoring if they were forced to use a van. They also suggested I use a Quad 303 or an A&R A60. I couldn't afford a 303 and I listened to an A&R A60 vs a Pioneer 6500 and preferred the latter.
After I left university I found myself in larger rooms, and really couldn't make the speakers work for me. I played with all sorts of things. Modified Videoton D100s were one of my favourites, Tangent SPL1, Royd Eden, and then got into designing (well, working with an acoustic engineer and an electronics engineer to design...) the Black Box prototypes that never made it to market. The LS3/5a in its original incarnation is a very specific thing, designed for a specific job, and more important than anything else for the BBC was consistency - hence the autotransformers and the calibration certificates. Having heard some Genelecs is a similar environment I feel we have progressed quite a long way in the last 40 years.