A great tour through Studio 2 by Rick Beato and Mirek Stiles.
https://www.youtube.com/watch?v=5HtA-vvXTKo
Mirek mentions Cliff and The Shadows a couple of times in relation to the introduction of amplified instruments but Rick has a bit of a fixation on the Beatles, I guess reflecting the relative lack of profile of our heroes in the USA. Also, I gather that it was Geoff Emerick who was the first to start breaking "the rules" in recording Cliff and The Shads and then took much of that later into the Beatles sessions.
Paul.