Maybe I've 'over egged' this one a little, but it was pretty interesting at the time.
Back in the mid 70s I was the UK "applications engineer" for a major US speaker manufacturer. We were in the process if selling EMI some new monitors for their 'rock' studios and I arranged for some of the technical people from the US to get a tour of Abbey Road.
The delegation from the US was pretty heavyweight so Ken Townsend, then Director of Abbey Road gave us the grand tour. It was interesting for various reasons, one being that Wings were in Studio 3 recording, among other things, Mull of Kintyre.
They were not there at that time in the morning, so we were able to wander around looking at the miking and general setup, all very interesting.
Most interesting though was the vinyl mastering and cutting 'suite'. Not much more than a back office in those days but apparently George Peckam was reluctant to move as he liked the sound of the largely untreated room. Our guys were pleased to see a pair of their 4310 monitors along with the ubiquitous Tannoys.
Mos of the interest though centered around the cutting lathe, (a Scully If i recall correctly) and the various mods that had been done to it. Of particular interest was just how precisely the groove width could be varied, enabling George to cut deeper than average bass and higher levels than was the norm at this time.
Legend had it that George, working at night mostly to benifit from reduced traffic noise, would set the groove width 'by ear', ie listening to the preview signal and adjusting the lathe by hand, in real time. This was considered rather more effective than relying on the automated system that was fitted to the lathe, bear in mind that this was pre computer and the automated system was pretty crude.
Still, I expect a lot has changed since those days, though "Porkies Prime Cuts' remain legendary to this day.